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Jekyll is a static site generator: it takes Markdown or HTML content, applies Liquid templates and layouts, and writes a complete set of plain HTML, CSS, and JavaScript files into an output folder (by default _site). You would use it when you want a fast, version-controllable site — typically a blog, documentation set, or project homepage — and you are comfortable editing text files rather than a database-backed CMS. It is not the same thing as OpenBVE, the train simulator project whose homepage happens to share the "Jekyll" keyword in site metadata; the two are unrelated.

How the build workflow fits together

Jekyll separates your source material from the finished site:

• Source files — Markdown (.md) or HTML pages, plus data files (YAML, JSON, CSV) and static assets like images.
• Templates and layouts — Liquid files that define reusable structure. A layout wraps a page; includes pull in repeated fragments such as a header or footer.
• Configuration — _config.yml holds site-wide settings: title, base URL, collections, plugins, and build options.
• Output — running the build writes the rendered site to _site/. That folder is what you deploy; it contains no server-side code.

A page's front matter (the YAML block between --- lines at the top of a file) tells Jekyll which layout to use and supplies variables the templates can read. Liquid tags then insert those values, loop over posts or collection items, and apply filters.

Common use cases

The GitHub Pages point is the one most people encounter first: pushing Markdown to a supported branch lets the host run Jekyll for you. If you need plugins that GitHub Pages does not allow, you build locally or in your own CI and publish the resulting _site instead.

What you need to start locally

1. Ruby — Jekyll is a Ruby gem, so a working Ruby installation is the prerequisite.
2. The Jekyll gem — install it with gem install jekyll (or manage it through Bundler).
3. A project — jekyll new my-site scaffolds a starter site with a default theme, a sample post, and a config file.
4. A local server — bundle exec jekyll serve builds the site and serves it, usually at http://localhost:4000, rebuilding when source files change.

Expected result: after the serve command, editing a Markdown file and saving it should update the page in your browser without restarting the server. If that does not happen, the usual causes are a missing gem in your Gemfile, a Ruby version mismatch, or a configuration error that the terminal output will name.

Where people get stuck

• Confusing the tool with a specific site. Search results for "Jekyll" mix the generator with unrelated projects that use the word in their metadata. Check whether a page is about static site generation before following its instructions.
• Editing _site by hand. That directory is regenerated on every build; changes there are overwritten. Edit the source files instead.
• Assuming hosting is automatic. GitHub Pages runs Jekyll for supported setups, but other hosts serve whatever files you upload — you must build first.
• Underscore-prefixed folders. Directories like _posts, _layouts, and _data are special to Jekyll and are not copied verbatim into the output; only their rendered results appear.

If your goal is a text-driven site you can version and deploy as static files, Jekyll is a direct fit. If you need a database, user accounts, or server-side rendering, a static generator is the wrong layer and you should look at a CMS or application framework instead.

GitHub is a web platform for hosting Git repositories and collaborating on code. For open-source projects like mailcow, it serves as the place where source code lives, releases are published, bugs are reported, and contributions are reviewed. You can use GitHub without writing any code — browsing a project's repository, reading its changelog, or filing a bug report are all legitimate uses. The one thing to keep straight up front: Git is the version-control tool that tracks changes to files, while GitHub is a hosting and collaboration service built around Git. You can use Git without GitHub, and GitHub hosts projects that use Git.

The core concepts you'll actually encounter

A repository's history is a chain of commits. Branches let people work on changes without disturbing the main line. When a change is ready, it's proposed as a pull request, reviewed, and merged. Issues are the separate track for problems and discussion — they aren't code, but they often drive it.

Finding a project's source, releases, and changelog

For a project like mailcow, the repository is the authoritative source for what's in a given version. A practical path:

1. Open the project's repository page. The file listing and README are the front door — the README usually states what the project is and how to install it.
2. Check the Releases section (often a link in the sidebar) to see tagged versions. Release notes typically list component version bumps and security fixes. mailcow's own blog, for example, publishes entries such as "Mootember 2026 | Unbound 1.26.1, SOGo 5.12.11 & Redis 7.4.11" and "Mooly 2026 | Postfix 3.10.12, Rspamd 4.1.0 & Nginx 1.30.3," each tied to a dated update release.
3. Look for a CHANGELOG file or a changelog link. This is where you confirm exactly which component versions and fixes landed in a release.
4. Use the commits view when you need to know when something changed, not just that it changed.

This matters when you're deciding whether to upgrade. A release note that says it "addresses several security-related issues" and "strongly recommend[s] updating" is a different signal than a routine dependency bump.

Reporting a bug or contributing a change

The workflow is the same across most projects:

• Before filing an issue, search existing issues. Duplicates get closed, and the answer may already be there.
• When filing, include what you did, what you expected, and what happened — plus version numbers. For a Docker-based project, that means the image or release version and relevant logs.
• To contribute code, the usual path is: fork the repository, create a branch, make commits, push, then open a pull request against the upstream project. Maintainers review, request changes, and merge.

You don't need commit access to any of this. Forking and pull requests exist precisely so outside contributors can propose changes without direct write access to the main repository.

GitHub vs. Git, in one example

Say you want to fix a typo in a project's documentation. Git, running on your machine, records your edit as a commit and tracks the branch you made it on. GitHub is where you push that branch and open a pull request so the maintainers can see and merge it. Git did the version tracking; GitHub did the hosting and the collaboration. If you only ever browse a project's releases or read its issues, you're using GitHub and never touching Git directly — which is fine.

Where this leaves you

If your goal is to use a project like mailcow, you mainly need the Releases and changelog views to pick and verify a version. If your goal is to report or fix something, you need issues and pull requests. And if you're trying to understand what changed between two versions, commits and release notes are the record — not the marketing page.

To generate an XML sitemap, you need your site's public URL and a site that search engines can crawl. You can then use an online generator, a CMS plugin, or hand-write the file. XML-Sitemaps.com, for example, generates search-engine-ready sitemaps and states that its free tier covers up to 500 URLs with no registration required. The steps below apply whether you use that tool or another generator.

What you need before generating

• The full starting URL of your site, such as https://example.com/.
• A site that is publicly reachable. Pages behind a login or blocked by robots.txt generally cannot be crawled or included.
• A decision on scope: homepage only, or the whole site.

Choose a generation method

XML-Sitemaps.com lists a free tier (up to 500 URLs, multiple websites) and a PRO tier starting at $2.44/month that adds automatic updates, image/video/news sitemaps, and SEO health reports. Treat those as the vendor's stated limits and check current terms before relying on them.

Understand the fields the generator sets for you

Two attributes are commonly filled in automatically, and knowing what they mean helps you spot problems:

• lastmod (last modification): the time a URL was last changed. Crawlers use it to avoid re-crawling unchanged pages. XML-Sitemaps.com says it sets this based on your server's response.
• priority: a value from 0.0 (lowest) to 1.0 (highest) relative to other pages on the same site. The generator decreases priority by "page depth" — how many clicks a page is from the homepage.

Neither field forces a crawler's behavior; they are hints. If your server returns unreliable modification dates, expect lastmod values that don't reflect real edits.

Generate and verify

1. Enter your site's starting URL in the generator and run it.
2. Download the resulting XML file (the generator may also offer HTML, text, or ROR formats).
3. Open the file and confirm the URLs are the ones you expect — correct domain, no staging or test paths, no duplicates.
4. Check that important pages are present and that the count matches roughly what you expect for your site size.

Submit to search engines

• Google: submit via Google Search Console (add and verify your property first, then submit the sitemap URL).
• Bing: submit through Bing Webmaster Tools.
• Place the sitemap at a predictable location, commonly /sitemap.xml, and reference it in robots.txt if you want crawlers to find it automatically.

Troubleshooting common problems

• Crawl fails or times out: the site may be slow, blocking the generator's user agent, or unreachable. Test the URL in a browser and check robots.txt.
• URLs missing: pages may be orphaned (not linked from anywhere), blocked by robots.txt, or behind JavaScript that the generator doesn't execute.
• Wrong domain in output: you likely started from a redirect or a staging URL. Start from the canonical public URL.
• Sitemap goes stale: a one-time generation won't reflect new pages. Re-run it, or use a tier/plugin that updates automatically.

If your site is small and static, a manual sitemap is fine. If it changes often or exceeds the free URL limit, an automatically updating option is the more practical choice.

Docker's official documentation lives at docs.docker.com, and it is organized so that a beginner can move from "I've never installed Docker" to "my app runs in a container" without leaving the site. The fastest path is: install Docker, complete the Get Started tutorial, then jump to a language-specific guide for your stack. Use the Reference section only when you need exact command syntax, and browse Samples when you want a working project to copy.

This guide explains what each section of Docker Docs is for, gives you a reading order, and shows you how to find things quickly once you're past the basics.

What the main sections of Docker Docs are for

Docker Docs is not a single manual — it's a set of distinct areas, each written for a different moment in your learning. Knowing which one to open saves a lot of time.

The key distinction: Guides and Get Started teach you by doing; Reference tells you exactly what a command accepts. Beginners often get stuck in Reference too early, reading option lists without context. Start with the doing, then look up the details.

A step-by-step reading path for your first container

Follow this order the first time. Each step has a clear "you're done when…" signal.

Step 1: Install Docker

Open the Get Started area and find the installation instructions for your operating system (Docker Desktop for Windows and macOS, or the engine packages for Linux). Install it and confirm it works by running the version check command shown in the docs.

You're done when: a docker command in your terminal returns version information instead of "command not found."

Step 2: Complete the Get Started tutorial

The Get Started tutorial is the single most valuable page for a beginner. It walks you through building an image, running it as a container, and stopping it — using a small sample app so nothing is left to guesswork. Do every command yourself rather than reading passively.

You're done when: you have built an image and seen your container produce output.

Step 3: Understand the core concepts

Before containerizing your own project, read the conceptual material on images, containers, and registries. This is where the mental model clicks: an image is the packaged blueprint, a container is a running instance of it, and a registry is where images are stored and shared.

You're done when: you can explain in one sentence why you build an image before you run a container.

Step 4: Write your first Dockerfile

A Dockerfile is the text file that describes how to build your image. Find the Dockerfile reference in the docs and read the instructions you'll actually use first: FROM, WORKDIR, COPY, RUN, EXPOSE, and CMD. Don't try to learn every instruction — most projects use a small handful.

You're done when: you have a Dockerfile in your project that builds without errors.

Step 5: Build and run your own app

Return to the Guides section and find the guide closest to your language or framework. These guides follow the same build-and-run pattern as the tutorial but applied to real application types, so you can adapt the steps to your code.

You're done when: your own application responds correctly from inside a container.

How to find things fast once you're moving

After the first container works, your needs shift from "learn the flow" to "look up one specific thing." Use these entry points:

• Search — the search box at the top of Docker Docs is the quickest route to a command or instruction. Type the exact command name (for example, a docker run flag) rather than a vague phrase.
• CLI reference — every docker subcommand, its flags, and examples. This is your lookup table, not a tutorial.
• Dockerfile reference — every instruction with syntax and notes. Check here before guessing at an option.
• Compose file reference — when your app grows to multiple containers, this defines them in one file.
• API reference — for when you automate Docker from code instead of the terminal.
• Samples — full projects organized by language and use case. Cloning a sample and modifying it is often faster than starting from a blank file.

A practical habit: when a command fails, copy the exact error into search. The docs pages for commands and instructions usually include the conditions that produce common errors.

Guides vs. Reference: which one do you need right now?

This is the distinction that trips up most beginners, so make it explicit:

• Use a Guide when you are trying to accomplish a task and don't yet know the steps. Guides assume you want an outcome and lead you there.
• Use Reference when you already know the task and need the exact spelling, flag, or field. Reference assumes you know what you're doing and just need precision.

If you find yourself reading a long list of options and feeling lost, you're in Reference too early — go back to a Guide. If you're following a tutorial and it doesn't cover the specific option you need, that's your cue to switch to Reference for that one detail, then return.

A reusable checklist for containerizing any app

Keep this sequence handy for each new project:

1. Confirm Docker is installed and running.
2. Identify your app's language and framework, then open the matching Guide.
3. Write a minimal Dockerfile using only the instructions you need.
4. Build the image and fix any errors using the Dockerfile reference.
5. Run the container and verify the app responds.
6. Add a .dockerignore file so unnecessary files aren't copied into the image.
7. When you add a second service (a database, for example), move to the Compose file reference.
8. Save the commands that worked so you can repeat them next time.

Where to go after your first container

Once one app runs in a container, the natural next steps are multi-container setups with Compose, sharing images through a registry, and automating builds. Each of these has its own Guide and Reference area on Docker Docs, so the same pattern applies: read the Guide to learn the flow, then keep the Reference open for exact syntax.

The documentation is large, but you never need all of it at once. Install, do the Get Started tutorial, containerize your own app with a language guide, and look things up in Reference only when you need a precise answer. That path takes you from zero to a working container without detours.