Javascript frameworks

Bootstrap uses two main libraries for its components. These libraries are Tether and jQuery.

Tether is a JavaScript library which is focused on the positioning of different elements in a web page. Bootstrap uses this library to define the position of the different components. ( In the new version tether has been replaced by Popper.js).

jQuery is a very powerful library. Using this, you can do with a few lines of code, things that otherwise need a lot of time and lines. Bootstrap uses this library to create the different JavaScript plugins ( modals, Popover etc).