List the type of locks and explain each of them.

There are primarily three types of locks:

• Shared lock - The shared lock allows two or more programs to be read from the locked space itself but it does not allow the viewer to modify it
• Update lock - It is a relatively more lenient type of lock, it slows the program to be read and it can also be modified
• Exclusive lock - As the name states, it restricts any user to access the locked space and its contents