You can iterate over more than one collection at the same time. This is what it means to zip collections together. By doing so, you can remove excessive iterations from your code. You can zip simple values and lists of maps, and you can lazy zip collections.
When you're working with large collections, iterating over them can be expensive, especially when there are several of them to iterate over. Sometimes this can't be avoided. For example, a value in one list might depend on a value in a few other lists in the same index. Rather than structure your code so that it requires several iterations, the zip() method can remove these excess iterations.
Instead of having multiple mappers or iteratee functions, you can tell the collection that several other collections are required as arguments passed to a single iteratee. This means that you have to be aware of the order in which lists are zipped.