Flash, or Adobe Flash is a set of multimedia software that was first released in 1996. Flash is used to create animation and interactive websites and pages. Flash can also be used to add video to websites.

Coda
Coda is an amazing multipurpose program created by Panic Softare for the Mac OS platform; it combines a text and CSS editor, FTP program (based on the already wildly succesful FTP tool for Mac, Transmit), terminal, web previews of your files, and even has a built in version of The Web Programmers Desk Reference. I absolutely LOVE this program because it eliminates the need for having multiple applications open and streamlines my web editing and uploading process. Unfortunately for PC users, Coda is only available for Mac.