IPFS
Url
It's a decentralized storage, shaped like a DAG, routing through a DHT.
Files can be updatable or inmutable.
Category
Accessible through
The IPFS program
Gateways
A local gateway can be operated just by running ipfs daemon
Readme
https://ipfs.io/ipfs/QmQPeNsJPyVWPFDVHb77w8G42Fvo15z4bG2X8D2GhfbSXc/readme
Hosted on IPFS, accessed through the ipfs.io gateway
Normal operations
https://ipfs.io/ipfs/QmQPeNsJPyVWPFDVHb77w8G42Fvo15z4bG2X8D2GhfbSXc/quick-start
Security
All files uploaded are accessible if some user get's hold of it's address, there's no way of making it available only for some group of users.
If you need security you should AT LEAST encrypt those files with a strong password, and make sure you know well what you are doing.
Although it's possible to create a private swarm and have the files not going out of it, it is not the normal mode of usage, and might not have the proper safety checks for operating it like that.
Files run from a local gateway via a browser might have attached JS, this will be run.