Template - the main part of the site page, which determines its design. The template does not require special syntax and is a regular HTML code (or possibly XHTML or another) with the call of the necessary chunks, parameters and snippets.
The number of templates most often depends on the appearance and functionality of the site. As a rule, different sections and pages of the site have their own templates.
For example, it would be logical to create different templates for product and news and attach different TV parameters to them. This will allow the content manager to quickly and correctly fill the site. It will also greatly facilitate the work of the programmer, if you need to make some news feeds or goods.
A chunk is a small piece of HTML code or other information that can be reused in a template, another chunk, or a snippet.
TV-parameter - an element that contains specific information for the current page. Parameters can be displayed directly on the page or passed to the snippet as a parameter.
A snippet is a PHP code that displays the result of its work in the place of the template/chunk where the call to this snippet is placed.
Typically, snippets are used to display dynamically changing content. They can be used to create menus, comments, news feeds, blogs, or any other functionality that is possible in the php language in conjunction with the Evolution system API.