On Twitter, unlike other social networks like Facebook and LinkedIn, the relations between users are not necessarily reciprocal, ie I follow a user and not is a prerequisite for that user to follow me, or vice versa.
Thus there are two types of relationships on Twitter: followers and friends, friends relationships are where both follow as they are followed by such person, in contrast to only follow, without having the follow back. Relations of friendship on Twitter, have a small advantage over the only followers.
Direct messages: If a Twitter user follows you and in turn you will you follow it, you can write direct messages (DM), also called private messages, so that anyone but you will see what you write. If only user1 follows user2, that user2 can send private message to user1, but not vice versa.
Followed Count Limits: On Twitter there are limits on the number of users that you can follow, and these limits are set by the ratio of people who still respect that follow you. If the ratio is unbalanced, Twitter does not allow users to follow more accounts until more people do not follow you, therefore, the ideal is that people follow you and be friends so you can follow more people that interests you.
Know if the Twitter user follows you:
To know if a Twitter user follows you, “the trick” is quite simple, you just have to go to their profile, ie http://twitter.com/USER_NAME next to the button and follow, if we click on avatar icon, to unfold the options, we see that among the possibilities available to the second is: “Send a Direct Message”. If on the other hand is not, and the second option we see is: “Add or remove lists ..” we know that we are following or not, that user does not follow us right now to us.
BONUS: One way that sometimes works for a user to follow us, especially if we think of normal, the user would follow us, but for whatever reason and did not realize when I started to follow, and so despite following he’s not following us. Is do unfollow him, ie to leave follow momentarily and immediately return to follow that person, this, will you receive a notification that you are following now, and therefore may, and I repeat, can only, that this person take interest in you and follows you. Add that it is not advisable to abuse more than once this resource because it can be counterproductive and even frowned upon by the person we follow.