Jekyll Blog: How to Write Blog Posts – Markdown "Hello World"

Jekyll has several nice features. The first one: the blog is static and built from posts written in Markdown. Below is a simple “Hello World” example – a few elements that I use most often.

The blog content is generated by Jekyll as a static site and served by GitHub. What I edit are plain text files in Markdown, with simple syntax. Below are the basic elements I use: headings, lists, code, and links. This is enough to write and publish a post. In addition, there is metadata: title, date, category, and tags.

Jekyll ensures that posts appear only when their date arrives. This makes it easy to schedule publications in a controlled rhythm.

Posts are stored locally in the _posts directory, with a very convenient filename format: date yyyy-mm-dd, then the name, and the .md extension. Example: 2026-02-07-jekyll-markdown-hello-world.md.

When I add new .md files to the local _posts directory, they are immediately visible locally at 127.0.0.1:4000, and on the live blog after commit and push.

So the workflow is simple: create a .md file, save it locally in _posts, commit and push – the post goes to the repository and appears according to its date.

“Hello World” Post in Markdown

Metadata (front matter / head)

At the beginning there is front matter (header) containing metadata recognized by Jekyll.

---                                      # Start of front matter
title: "Hello-world markdown for Jekyll" # Displayed as page heading
description: "Example of Jekyll front matter (YAML) structure with basic metadata fields."
date: 2026-02-06 08:00:00 +0100          # Publication date and time; used by Jekyll for sorting and publishing
categories: [Blog]                       # Post category (or list of categories)
tags: [blog, jekyll]                     # List of tags for classification and filtering
---                                      # End of front matter

Directory Structure Convention

Posts are placed in the Jekyll “special” directory _posts. The filename example: 2026-02-07-jekyll-markdown-hello-world.md.

All materials related to a given post are stored in a separate directory:

assets/
└── posts/
    └── jekyll-markdown-hello-world/
        ├── cauchy.png
        ├── plot.svg
        ├── data.csv
        └── cauchy.pdf

This directory contains all files related to the post: images, PDFs, auxiliary data, etc.

In the post content, I reference them by path :

[Caption](/assets/posts/jekyll-markdown-hello-world/cauchy.png)

Post Content (content / body)

The content begins directly after the metadata.

Text is plain text, e.g.: “I created a blog, so the question arose what to write so that the blog has at least one post.”

Text formatting: bold, italic, bold and italic, bold and italic.

Text formatting: **bold**, *italic*,
***bold and italic***, ***bold** and italic*.

Links

A link like this: https://marcinszewczyk.net/

[link text](https://marcinszewczyk.net/)

Headings

They are used for table of contents, anchors, and SEO (Search Engine Optimization):

# Level 1 heading
## Level 2 heading
### Level 3 heading

Figures

Example figure:

Fig. 1. Geometric interpretation of Cauchy’s theorem.

Code:

<!-- note: no blank line between the image and the caption -->
![Cauchy’s Theorem](/assets/posts/jekyll-markdown-hello-world/cauchy.png)
***Fig. 1.** Geometric interpretation of Cauchy’s theorem.*

Linking to files: same as above, just without “!”.

Lists

Unordered list:

• list item
• text – bold
• text – inline code

- list item
- **text** -- bold
- `text` -- inline code

Ordered list:

1. list item
2. text – bold
3. text – inline code

code

1. list item
2. **text** — bold
3. `text` — inline code

Code

Inline code:

`inline code`

Code blocks.

Bash:

```bash
git clone https://github.com/...
```

Result:

git clone https://github.com/...

Markdown:

```markdown
title: "Hello-world markdown for Jekyll"
...
```

Result:

title: "Hello-world markdown for Jekyll"
...

Python:

```python
print("Hello, world!")
...
```

Result:

print("Hello, world!")
...

C:

#include <stdio.h>

int main(void) {
    printf("Hello, world!\n");
    return 0;
}

LaTeX:

\documentclass{article}

\begin{document}

Hello, world!

\end{document}