Regular expression

A regular expression is like a pattern that you can use to search for certain types of words or phrases in a bigger set of text. For example, let's say that you wanted to find all the words that ended with the letter "l" in a book but didn't want to search for every single word one at a time. You could use a regular expression to help you out. In this case, you could use a pattern like this: l$ which would look for any word that ends in "l". The computer will then go over the book and find all the words that end in "l" and give them to you.