Grid System in Bootstrap 3
Grid system is one of the most important features in Bootstrap. Grid system helps you in arranging your web page content in proper manner. It is basically a combination of rows and columns. You can have multiple rows, but each row will have only 12 columns. Grid system is rectangular in size which contains all the rows and columns just like a table element in HTML. Thus, it adjusts itself depending upon screen size of a device.
Grid System in Bootstrap – 1 Row 12 Columns