What is Threads and what is its relationship with the fediverse?

Activitypub is the standard all the fediverse application use, and that's what makes the various apps cross compatible (you can reply to a Lemmy thread from another Lemmy instance, or from a kbin one or even from Mastodon).

This standard is used by various WebApps to provide social networks experiences akin to the big centralized networks.

Lemmy and kbin work like reddit.

Mastodon and pleroma do microblogging (default message length is 500 char, can be modified on each server though).

PeerTube is a distributed YouTube alternative, again using activitypub to federate.

Now thread is a new microblogging app by Instagram and it happens to use activitypub, which means it could be interconnected with fediverse apps. You could in theory follow and interact with its users from any of the fediverse apps. But this feature is not on from their side at the moment. And many fediverse server admins plan to block federation with threads.net because they don't trust Instagram / meta.

Good , permablock them for life and beyond.
Mastodon and pleroma do microblogging (default message length is 500 char, can be modified on each server though).

IIRC, Pleroma defaults to something significantly-longer.
- Correct. It's hard to give generalities and be correct on all the details, as you know.
Some people are claiming that it’s going to ruin the fediverse. Could that actually happen?
- What could happen is what did happen to XMPP / jabber.
  Google embraced it for its instant messaging app, then after it had become the provider with the largest user base of said standard, it simply changed the underlying tech it used and stopped using the standard. To google users, their weird contacts that were not on the google ecosystem simply vanished, but they were a small number of people. To the users of xmpp servers, many of their contacts on the google side of things became unreachable again.
  
  Now that's a thing that can happen if threads.net becomes the largest fediverse instance over time and loosing access to these users is a big detriment to users of other instances.
  
  However, I couldn't care less if I lose access to the posts of threads.net users. I don't intend to interact with them at all. I don't use any mainstream social media at the moment, and I don't miss the ads, the drama, and the "normie" users, for lack of a better term.
- It'll install the usual Chinese and Chinese disinformation bots and companies like Cambridge Analytica.

ActivityPub is the underlying tech that allows for this federated universe (fediverse) of connected servers talk to each other so posts can be seen from other servers. Mastodon is built to use this just like how Lemmy, kbin, PeerTube, misskey, and others are.

As long as two servers are “federated” with each other (open to talking to each other and see each other) then users can see posts from each other’s community. This is where the issue with Threads begins. Fediverse users suspect that Meta is using the fediverse as a kind of data-collection-Trojan horse since it plans on having an ActivityPub interface. Besides that, Threads users will likely bring more toxic commentary with them.

That’s the gist of what I’m getting from other community members. If anyone can put it better then please feel free to correct me or add on/clarify.

Pls ban threads and meta and block them out of everything. Zuckerdick must be locked up.

If activitypub is open source, now is the time to lock it under a license that forbids unethical data gathering.

I prefer forums. The tech behind fediverse and whatever stuff is just too hidden. I think in a matter of months everything goes back to forums. Also, go back to old mmos. They are the best.
- The tech behind fediverse and whatever stuff is just too hidden.
  
  In what possible sense is it hidden? You can literally read all the code. The specs are published by the W3C, just like HTML.
It's a system for publishing your posts and comments. That is literally what it is for: making them public. When you post, you thereby willingly surrender control over whose computer your message might be copied to.

The Lemmy server software, in particular, defaults to open federation. This means that the "normal" mode of operation is literally to permit absolutely anyone anywhere in the world to read (or otherwise process) whatever you're posting.

So you can't reasonably expect to prevent or deter someone from using the material that you have caused to be delivered onto their own hard drive.

It would be interesting to require as a condition of federation that all posted content be placed under a share-alike license like CC BY-SA: you may do whatever you like with it, but you must cite your sources, and the work you create thereby must also be reshareable under the same terms.