Snippets are reusable test cases in scope of project. So you can create a snippet and refer to it in your test suites. For example, to login a user we need to perform multiple actions: visit login form, fill it out and submit. Instead of adding these test steps to every test case for logged in user we can simply create once a snippet and then refer to it from many test cases. Besides, to every reference we can assign a set of template variables that can be addressed in the body of the snippet. In other words, we can execute the same snippet, but giving it a different input every time.