A few posts ago, I introduced you to Bootstrap, an HTML+CSS framework that makes formatting websites and pages easier. There are lots of advantages to using Bootstrap, but one of its biggest advantages is the grid system.
Think of the grid system as a piece of graph paper, with every page containing horizontal and vertical lines. Squares and rectangles form when the lines intersect.
Bootstrap allows you to create up to 12 columns and an unlimited number of rows, quite useful when designing a page.