InterPlanetary File System. A completely decentralized file sharing technology. This is a backend file service that MANY decentralized services and apps rely on. Think of it as a global, public, temporary hard drive. The 3 gateway links below MUST be followed by an IPFS file hash to work. They exist as a gateway to the legacy web that you're using now. IPFS does NOT "have" a website. There IS "a" website that tells you about it and lets you download the software, but IPFS, itself is NOT a website and does NOT USE a website. This is critical to understand. It's a peer to peer global TEMPORARY hard drive with no central servers. Files are TEMPORARILY cached as they're accessed by users, apps, & services. They go away if not accessed for a long time, unless they're seeded. IPFS is NOT a permanant storage system. It's a publication system. Use services like Pinata if you want your files to stay accessible.
IPFS will work without centralized DNS.
It will work without central servers.
It's unknown or not applicable as to how user accounts are handled. It's unknown or is not applicable if IPFS supports cryptocurrency monetization.