IPFS is a protocol that defines a content-addressed file system, coordinates content delivery and combines ideas from Kademlia, BitTorrent, Git and more.
IPFS is a filesystem. It has directories and files and mountable filesystem via FUSE.
IPFS is a web. Files are accessible via HTTP gateways like https://ipfs.io. Browsers can be extended to use the ipfs:// scheme directly, and hash-addressed content guarantees authenticity
IPFS is p2p. It supports worldwide peer-to-peer file transfers with a completely decentralized architecture and no central point of failure.
IPFS is a CDN. Add a file to your local repository, and it's now available to the world with cache-friendly content-hash addressing and bittorrent-like bandwidth distribution.