What is the difference among col-lg-*, col-md-* and col-sm-* in Bootstrap?

Question

What is the difference among col-lg-* , col-md-* and col-sm-* in Twitter Bootstrap?

Answer 1

TL;DR

.col-X-Y means on screen size X and up, stretch this element to fill Y columns.

Bootstrap provides a grid of 12 columns per .row, so Y=3 means width=25%.

xs, sm, md, lg are the sizes for smartphone, tablet, laptop, desktop respectively.

The point of specifying different widths on different screen sizes is to let you make things larger on smaller screens.

Example

Meaning: 50% width on Desktops, 100% width on Mobile, Tablet, and Laptop.