You must have noticed that some tweeps add periods/dots/full-stops right in front of handles when the handles come first place in a tweet. Well, it is a trick for determining what comes up on your Twitter timeline.
Normally, when you reply or tweet directly at a handle (by mentioning the handle at the beginning of your tweet), the tweet only shows up on timelines of those who follow you and the handle mentioned. But when you add a period or RT before the (@)handle at the beginning, everyone who follows you gets to see the tweet.
Take a look at your Twitter profile on desktop. You’d notice that your own timeline is divided into 3 categories – tweets, tweets & replies, photos & videos. Tweets with period before the handle at the beginning fall under Tweets while those without periods fall under Tweets & Replies.
Tweets that are conversational in nature such as the tweets below are hidden from those who don’t follow the participants of the conversation. This is a way to stop other people from crowding your timeline with tweets that might not interest you.
This rule works only for desktop.