Jekyll is using something so-called Front matter which is used to set variables or page’s metadata on a page and use them on runtime. YAML front matter must always be at the top of the document:

---
layout: post
title: MySQL Scheduled Backup
---

So the front matter is a right place for defining tags for pages. All we need to do is set a tags variables just like this:

---
layout: post
title: MySQL Scheduled Backup
categories: [MySQL, Database, Backup, Scheduled Task, Windows]
---

The we can use it all over the project this way:

{% for category in page.categories %}
<li>
  <i class="fa fa-tags"></i>
  <span>
  	{{ category }}
  </span>
</li>
{% endfor %}

For example, we can encapsulate this piece of code as a file called _tags and put it inside _includes directory. Then we can include it wherever we want:

---
layout: default
---

<article class="post">
  <h1>{{ page.title }}</h1>

  <div class="entry">
    {{ content }}
  </div>
  {% include tags.html %}
</article>