Smart Blocks allow you to set and edit content once and have it show anywhere where you add the smart block [TAG] to your content.
It also allows you to update content in one place and have the content update anywhere the [TAG] is used.
It is useful for adding facebook widget embed code or other code-based widgets which cannot easily be added using the Drag-drop and Contentbox editors.
It is also handy for repeatable content such as Size Guides or Staff Bio information e.g. for the writer of a set of blog posts.
Smart blocks can be found under the Design tab -> Wording / Language heading -> Smart Blocks.
You will be shown a screen where you add new smart blocks or manage your existing ones.
If you have been given some code and html to add to your page you can paste this in HTML mode. While you can add content using TINYMCEs HTML button found in the toolbar, TINYMCE may strip out code it does not like.
To use a block on your website you need to add smart block tag into your content area as text.
This can be added to any content area when editing content.
For example if you put your terms and conditions in a smart block then added the tags in relevant places, you would only need to edit the smart block content once for it to update everywhere it is used.