The Structure Editor is used to create Structure data types.
A structure provides a convenient alternative to a MemoryBlock as they are also often used to group together information for external function calls.
The values of structures have specific sizes giving the structure its own specific size.
You typically only use structures when you have very specific memory or performance requirements or when you need to interface with an outside API that requires a structure. In most cases, you will want to use Classes with appropriate properties for your data management.