The Forever block is a Control Block and a C Block. Once the block is activated, all blocks inside of it will be read "forever", forming a loop - the only way to break it is for the project to end or a Stop Script/Stop All block to be read.
The Forever block has one of the most interesting shapes in Scratch. Its shape is a cross between a C Block and a Cap Block. This prevents blocks from being placed on the bottom of the block, as these blocks would never activate.
The forever block is one of the most commonly used in Scratch. To many projects, such as games requiring a loop, this block is vital. If an if block is included in a script, it will most likely be placed inside a forever block. Some of the other many uses of the forever block are:
- Operating System windows (The sprites contained in them are often moved)
- Certain math projects (such as a project to calculate the value of pi)
- Sound projects
- Some animations