Hubs are general-purpose websites. You can decide what you want them to do. These may have one or more members. Every hub member can create or customise their own "channels", which are personal websites, forums, media collections, and/or social spaces within the hub, and these can all share and interact.
Hubs and their members from all over the internet connect together "magically" to create very large communities and social networks; and these can all share and interact.
Hub members can securely and privately share anything; with anybody, on any hub - or share stuff publicly with anybody on the internet if desired.
Hubzilla is the server software which makes this possible. It consists of an open source content management system combined with a decentralised identity, communications, and permissions framework and protocol suite, built using common webserver technology (PHP/MySQL/Apache, although Mariadb or Postgres and Nginx could also be used - we're pretty easy). The end result is a level of systems integration, privacy control, and communications features that you wouldn't think are possible in either a content management system or a decentralised communications network.
Hubzilla hubs are
decentralised
inherently social
optionally inter-networked with other hubs
privacy-enabled (privacy exclusions work across the entire internet to any registered identity on any compatible hubs)
Possible website applications include
decentralised social networking nodes
personal cloud storage
file dropboxes
managing organisational communications and activities
collaboration and community decision-making
small business websites
public and private media/file libraries
blogs
event promotion
feed aggregation and republishing
forums
dating websites
pretty much anything you can do on a traditional blog or community website, but that you could do better if you could easily connect it with other websites or privately share things across website boundaries.
