Reading Key: If you are familiar with SharePoint 2007, you will probably find this entire chapter interesting and important.
By now, you should be familiar with the basic concepts of SharePoint. You should also understand writing features and solutions, and packaging WebParts and pages as features and solutions.
Writing WebParts and pages is critical for any SharePoint developer. However, most of that code runs on the server. This is very much like the world we used to live in during ASP.NET 2.0 times, when any rich functionality you wanted to provide to the end user required you to cause a postback.
The reality today is a little bit different. Web applications are extremely rich ...