jsPlumb provides a way to connect elements in a UI.
This page contains examples of the various types of connections you can make.
There are several other demonstrations that offer a more focused look at some specific part of jsPlumb's functionality - pick one from the drop down or cycle through Next/Previous.
jsPlumb requires one of jQuery, MooTools or YUI3. See the documentation for a more detailed discussion of requirements.
This demonstration uses jsPlumb 1.5.5, jQuery 1.9.0 and jQuery UI 1.9.2.For touch support, jQuery Touch Punch is used.