Bootstrap is the most popular front end framework around the globe now. It Used for building responsive, mobile first websites and web

1. col- (extra small devices - screen width less than 576px)

2. col-sm- (small devices - screen width equal to or greater than 576px)

3. col-md- (medium devices - screen width equal to or greater than 768px)

4. col-lg- (large devices - screen width equal to or greater than 992px)

5. col-xl- (xlarge devices - screen width equal to or greater than 1200px)

6. col-xxl- (xxlarge devices - screen width equal to or greater than 1400px)

The classes above can be combined to create more dynamic and flexible layouts.

!Tip: Each class scales up, so if you want to set the same widths for sm and md, you only need to specify sm.