Recently a customer was asking about how Sticky is installed:
I also like your sticky cart app. Does that also install via a snippet?
If you've never heard of a snippet before, it's a Shopify theme term that is used to describe a chunk of code that is kept in a separate file.
You can think of them as mini-templates that can be added into your theme's pages are various points.
Sticky is installed via a snippet.
After signing up Sticky's server will create the snippet and add it to your theme automatically. Inside that snippet is all the code that Sticky needs to run.
You too can experience the magic and wonder of Sticky's installer when you install.
(It's not really that magical or wonderful, just a regular ol' automatic installer...)