If you have decided to take the google analytics course then you would have to add regular expressions in your learning list. Regular expressions make the job whole lot easier to create more powerful implementations. You can use Regular expressions for multiple purposes, some of them are listed below:
To check if the text contains a certain pattern
Make changes to the text
Regular expressions is mostly used when dealing with strings. So here are some of the resources you would use to learn regular expressions.
Here is a great online tool for creating, editing and validating regular expressions.