On July 2nd 2013 Twitter changed their automation Terms and Conditions banning automated following and unfollowing.
http://support.twitter.com/articles/76915
Automated following and un-following
You may not use or develop any service that allows for the following or unfollowing of user accounts in a bulk or automated manner. Accounts and applications that engage in this practice will be suspended. Please review our Follow Rules and Best Practices for a detailed discussion of following recommendations.
Also note that per the Twitter Rules, "get followers fast" applications and services are not allowed. Do not surrender your username and password to them, or otherwise grant access to or control of your account to any third party apps that claim to provide such services.
What that means to applications? It means applications that still offering automated following and unfollowing will be banned from using Twitter APIs. They Twitter API access key will be suspended.
What that means to Twitter users? It means users that continue using such automated following and unfollowing will be suspended.
Can I buy followers? If they will follow you manually - yes. If they will follow automatically - no. Can this be fast (get fast followers) - NO.
Why people used such automated tools? The idea was to grow your Twitter user, get as much followers as possible in relatively short period of time, i.e.
Get Twitter Followers Fast.
How exactly it was done? You follow as many people as possible till you reach Twitter following cap of 2000. Some people will follow you back (some manually some will follow back automatically. Then you use app that finds all Twitter users that not following you back, and unfollow them automatically.
That way you keep your following/followers ratio and can follow more. Leaving your user on auto-pilot you can grow your Twitter user to 10's or 100's thousands of followers, and of course you follow also 10's, 100's thousands.
Why people want this kind of users in a first place? Get more influence, your tweets can make better to top tweets, get paid more for paid tweets.
After Twitter banned automated following and unfollowing, what are the options to grow your Twitter account? Tweet interesting things, mention (but not too much) others with similar interests of yours, reply/retweet others.
And of course you still can do same following and unfollowing, but manually using tools that help you find whom to follow.
You still can follow many people every day. Using our
Twitter Auto DM service you can see all your new followers with many details and stats, and follow them back one by one, manually.
You can use our app to
find who unfollowed you or not follows you back and unfollow them manually, one by one. It is not automatic, but we bring all Twitter user's data and buttons on the same screen, making your manual work efficient as possible.
Read also:
Twitter Bans Automated And Bulk Following In Controversial TOS
Get the Best Twitter Marketing Software and more Twitter Followers