About content reuse
You can embed content from one file inside another using includes. Put the file containing content you want to reuse (e.g., mypage.html) inside the _includes/custom folder and then use a tag like this:
{% include custom/mypage.html %}
With content in your _includes folder, you don’t add any frontmatter to these pages because they will be included on other pages already containing frontmatter.
Also, when you include a file, all of the file’s contents get included. You can’t specify that you only want a specific part of the file included. However, you can use parameters with includes. See the following Jekyll cast for more info about using parameters with includes:
Page-level variables
You can also create custom variables in your frontmatter like this:
---
title: Page-level variables
permalink: page_level_variables/
thing1: Joe
thing2: Dave
---
You can then access the values in those custom variables using the page namespace, like this:
thing1: {{page.thing1}}
thing2: {{page.thing2}}
I use includes all the time. Most of the includes in the _includes directory are pulled into the theme layouts. For those includes that change, I put them inside custom and then inside a specific project folder.