How do reply tweets work on twitter?

[Intellectualbun992]

This is a little embarrassing to ask because I have been on twitter for quite a while and I was wondering about how reply tweets even function. Hypothetically speaking, If I posted a tweet and someone adds a reply tweet to me, is it possible that the reply can be deleted any other way than me manually deleting it from my tweet? ( I am fully aware that you can't delete a reply tweet fully that is made by an other user. )
I was also wondering if twitter has any kind of hidden advanced option to limit reply tweets to only certain followers or twitter users that reply to any tweet I decide to post?

[Akhand]

Starting my update with "@veronica" designates that I'm addressing her, specifically, much as you would in a group conversation. Also like a group conversation, she's not the only one who can see what I'm saying. If I wanted to "whisper" something instead, I'd start my message with "d veronica"—what we call a "direct message." (A person must be following you in order for you to direct message them, but not to @reply them.)

As you may know, @replies were not originally part of Twitter. They were embraced by the community first, and then we built them into the system. First, we linked the username (when using the web interface), then we added a replies tab, so you could see replies to you from people you weren't following. We also added a setting to determine what @replies you see (more about that in a minute). And most recently, we added the "swoosh" to the web interface, so you could more easily reply. Other Twitter clients have also embraced @replies in cool ways.

Today, @replies are a critical part of how Twitter works. However, they're not perfect. In fact, some people are either loath to use them or annoyed by them (or both). I believe a big reason for this is that's it's not obvious exactly how they work. In fact, I talk to even advanced Twitter users on a regular basis whom I end up explaining what the @replies setting does and who see what replies.

@Replies To You
If someone @replies you—note, this means they start a tweet with @yourusername—you will see that in your main timeline if you follow the person. But you'll see it in your replies tab, whether you follow them or not (unless you've blocked them),