It's most advertised use case is fact logging or data validation and authentication, but it's a data layer. It's a ledger set up in a very data-friendly manner so there are many things you can do on it. For example, several of the ANOs are developing the FAT protocol, which is tokenization on top of Factom.
The Factom Protocol is decentralised; no one knows how many customers each ANO has, or how many other companies are building on the Protocol without being associated with an ANO.