Scratch is a web application that serves as an introductory tool that aids students’ advancement in the more sophisticated programming languages in a visual way. It uses graphical blocks (such as graphics, photos, music, and sound) to represent program commands. Students can then post their creations on the Scratch site, where others can view and download them. Scratch is always will be free. You don’t need a license to use Scratch in your school, home, or anywhere else.
Students can use Scratch to design anything they want in various forms such as games, animation, or movies. This provides great motivation for learning. With one-click, a user can view the result of a partially-constructed product, allowing and promoting constant self-correction and analytical thinking. It is used in many school districts to promote learning for academic subjects such as math and science and can be a great tool for constructive learning and project–based learning.
Take a look at this Walkthrough to give you a better understanding of Scratch.
Alternatively, when you load the Scratch website, you see galleries of programs created by other users. Click a thumbnail to see a description page, which provides coder-provided information about each program. You can play them, share them, or—best of all—"see inside." This lets you see how the coder created the program. It's a great way to learn how other people program and to pick up tips on how to build things.