When you think of document storage, you probably picture boxes and boxes of forms: job applications, memos, employee information, etc. But those standard pages you're thinking of are not the only documents that your business might need to store, and they're not the only documents that a records storage facility will take care of for you.
Depending on your business needs, you can store all sorts of things, physically or digitally. A company in the medical business, for instance, might need to store x-rays or other sensitive medical documents. Records storage facilities know how to take care of those sorts of documents, and will ensure that your records are always in the best of shape.
You might also find that you need to store irregularly shaped or oversized items, like architectural renderings. Not a problem. A records storage facility can meet your needs.
What about documents that aren't traditional documents, such as a cassette tapes, DVDs, CDs, microfiche, etc.? Again, you will be able to find a records storage facility that can work with you to allow you to store exactly what you need to store.
It might help you to think of records storage facilities the way you would think of your standard storage facilities. Other than flammable or other dangerous goods, "normal" storage companies allow you to store whatever you need. Records storage facilities will do the same, with regard to records.