Ruby, Difference between exec, system and %x() or Backticks

Question

What is the difference between the following Ruby methods?

exec, system and %x() or Backticks

I know they are

Answer 1

They do different things. exec replaces the current process with the new process and never returns. system invokes another process and returns its exit value to the current process. Using backticks invokes another process and returns the output of that process to the current process.