Bootstrap well is a container <div> that makes the content to appear sunken or an inset effect on the page. In order to create a well, wrap the content that you would like to appear in the well with a <div> containing the class of .well.
Bootstrap includes a responsive, mobile first fluid grid system that appropriately scales up to 12 columns as the device or viewport size increases. It includes predefined classes for easy layout options, as well as powerful mixins for generating more semantic layouts.
Button groups allow multiple buttons to be stacked together on a single line. This is useful when you want to place items like alignment buttons together.
Bootstrap container is a class which is useful and creating a centred area in the page for display.
Fluid layout adapts itself to different browser. Means design automatic adjust according to browser size.
As the name suggest this component can optionally increase the size of headings and add a lot of margin for landing page content. To use the Jumbotron −
☛ Create a container <div> with the class of .jumbotron.
☛ In addition to a larger <h1>, the font-weight is reduced to 200px.
<span class="badge"></span> in LI Tag
This class allows to float a media object (images, video, and audio) to the left or right of a content block.