Quoted:
I hear about it all the time... Hash tag this and hash tag that. How do you do it and how could you possibly know someone is tweeting if they didn't first tell you they were? Seems much more complicated than sending a text message on the cell phone. Thanks!
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Yes and no.
1) You normally see posts made from people you follow, people who "mention" you
- you also see when people "mention" you - @yourusername <message> etc. (kinda like an open letter)
- you also see when people send you direct messages - private <-- This is as similar as you can get to a text message etc.
2) If you know someone's username you can read all of their public posts & mentions
3) You can click on hashtags that someone posts and see posts made by others who used the same hashtag
so yes it is more complex than just texting a single person. but it's not intended to only be a private message between two people. That is an option of course, but not the only one.