Twitter can help you find friends and colleagues who are on Twitter by looking up contacts from your email address book. You'll be able to find and follow contacts who've opted to allow others find them by their email address. Click here to learn how to find friends via Twitter search.
You can remove imported contact info from Twitter at any time. (Note: Your Who to follow recommendations may not be as relevant after removing this info.)
Read our troubleshooting tips in our I'm Having Trouble with Following article.