SSI (Server Side Includes): a new page in my site

I'm taking an online course in how to use SSI. I've created this new site page for my own bookmarks and all links to resources.

What is an 'include'? When you have sections that are the same on each of your pages, as in a navigation menu, when you want to make changes it can become a nightmare if you have more than a couple of pages. The best way to get around this is to use 'includes' (server side includes).

An 'include' file is a text file, which contains the section of the webpage that you want to remain the same on each page. When you want to make changes, you change the text file, then upload it to your webspace. You note on your html page the name of the text file to 'include', then when someone loads the html page it pulls the html from the 'include' and anyone who views your source can't tell you have done it this way. [explanation is from HTML Basix]