Regex that Detects specific string pattern

Question

I'm new to Regex. The question asks me, Come up with a Regex that Detects specific string whether in start, middle or end of a string with Regular Expressions?
Try it yourself before checking the solution below:

I first thought the solution would be this:

  (?:^\s+)|(?:\s+$)

The solution is this:

  (?:\s|_)ra(?:\s|_) 

How does this Regex work?

Can you walk me through each step? What does this line of Regex do? Please help me out.

Answer 1

I was able to find answer to my question. I will close the post now.