Add span with .input-group-text class before <input> for input-group-prepend and add span with .input-group-text class after <input> for input-group-append.
While multiple <input>s are supported visually, validation styles are only available for input groups with a single <input>.
Multiple add-ons are supported and can be mixed with checkbox and radio input versions.
Input Groups can use with checkboxes and radio buttons also. For it add code for .checkbox class and .radio class respectively.
Add .input-group-{lg/sm} class to .input-group for Large/Small addon/prepend.
Add <button> with .dropdown-toggle class and add dropdown-menu after it to get input group with dropdown.