Recently found a really cool site : https://scrimba.com/ for learning how to code new languages and thought I would share my notes 

Tables

12 Columns width by default needs to be divisible by this

Small Screen : Width 6 : col-sm-6

Medium Screen : Width 3 : col-md-3

Can be classed together e.g. col-sm-3 and col-sm-6 

Modal

 is a popup box with a greyed out background using Java

List groups

for notifications e.g. number Message waiting or special offiers

Nav Tabs 

Great for Grouping content on a single page instead of navigation, uses Ajax to display real-time