Although not necessary: Writing Code for Forms provides a way to increase interaction between the user and the entity forms. This is often done by using JavaScript that is executed for events that occur on the form.
Microsoft Dynamics CRM 7.1.0 (2015) offers TURBO Forms which are seriously worthy of consideration, both for the Experienced Dynamics CRM Developer and for the CRM end user. Performance differences have been clocked anywhere from 3x to 7x times faster.
Here are some materials and videos to help get you started.
Microsoft Dynamics CRM Online 2015 Update 1 - New Form Rendering Engine
Writing code for Microsoft Dynamics CRM 2015 or CRMOL Forms : Read More