To set key stuff on an element, use the .bg-primary class in Bootstrap.You can try to run the following code to implement .bg-primary class that is blue in color −ExampleLive Demo           Bootstrap Example                                 Example             Danger       Key text!          

To set the width of an element to 100%, use the .w-100 class in Bootstrap.You can try to run the following code to set element’s widthExampleLive Demo           Bootstrap Example                                          Set element width          Normal width          Width is 25%          

Use the .btn-danger class to set danger action for a button i.e. red background color to an element.You can try to run the following code to implement danger action −ExampleLive Demo           Bootstrap Example                                          Categories                      Tech 95          Entertainment 30          Research 9          Viral 20          Sport 105                      Do not click below:          Danger          

Use the .btn class in Bootstrap to create a button.You can try to run the following code to create a basic button in Bootstrap −ExampleLive Demo           Bootstrap Example                                          Categories          Tech 95          Entertainment 30          Research 9          Viral 20          Sport 105                      Our blog posts          Click to visit          

Use the .btn-block class in Bootstrap to create a block-level button.You can try to run the following code to implement .btn-block buttonExampleLive Demo    Bootstrap Example                                          Categories                      Tech 95          Entertainment 30          Research 9          Viral 20          Sport 105          

Use the .badge class in Bootstrap to create a circular badge with Bootstrap.You can try to run the following code to implement .badge class −ExampleLive Demo           Bootstrap Example                                          Blog Posts          Tech 95          Entertainment 30          Research 9          Viral 20          Sport 105          

To create a yellow color alert box indicating a warning action, use the alert-warning class.To implement an alert-warning class, you need to try to run the following codeExampleLive Demo           Bootstrap Example                                          Indicates a positive action!                      Indicates warning!          

To create a green color alert box indicating a positive action, use the alert-success class.To implement an alert-success class, you need to try to run the following code −ExampleLive Demo           Bootstrap Example                                          Indicates a positive action!          

To set the width of an element to 25%, use the .w-25 class in Bootstrap.You can try to run the following code to set element’s widthExampleLive Demo           Bootstrap Example                                          Set element width          Normal width          Width is 50%          Width is 25%          

Use the .alert-info class to create a light-blue alert box indicating some information.You can try to run the following code to implement .alert-info class in Bootstrap −ExampleLive Demo           Bootstrap Example                                                       Information!             Add information here...