XPath is a way to find elements based on where they are in the Document Object Model (DOM) hierarchy. This is a great way to get a unique identifier since the path to a particular element on a page is going to be unique, but there is one big challenge with this in terms of maintaining your tests going forward. Since the XPath locator for an element usually includes a lot of the element hierarchy on the page, any changes to the page hierarchy (for example, due to changing the page layout), will make that XPath invalid.