Google Analytics uses different types of techniques to identify URLs when configuring a destination goal or a funnel. One of those types is Regular Expression.
Regular expressions are patterns used to match character combinations in strings. Most of the filters included in Google Analytics use these expressions to match the data and perform an action when a match is achieved. This needs an example:
Imagine that you have two thank you pages on you site:
- /Thanks for the subscription page to your blog and
- /Thank-you for the shopping cart.
If you want to track both pages on the same goal, you will need a regular expression to match both URIs even if they are different. In this case you will use the following regular expression: Thank(s|you)
You can test your Regular expressions at Regex101. Heres is the same example tested on their tool:
Read more about Regular Expressions in the Google Analytics Help Center.