What are ZIP files?

Where exactly did you run into this term? I ask because ZIP stands for several things in various regions.

ZIP is an archive file format that supports lossless data compression. 

ZIP (Zone Improvement Plan) also stands for postal code in the US.

Axel F.

See if this support article can help you:--> How to open ZIP files on your iPhone, iPad, or iPod touch

If you mean something different, please specify your needs better.

Regards

Giulio