This is unique and the most favorite feature on Tweet Adder. You can laser targeting people you want to follow based on keywords (terms) on their tweets and their profile. For example, you want to follow people who like "basketball", then you can use this feature to target them.
Why you need to follow other people? Just by following people may be not usefull. But imagine what happen next after you follow them? Normally, most of them will follow you back! This is what we want! So, by targeting people you follow based on the keyword you set, you have a big chance to get followers with the same interest as you want. When you offer things related to their interest, mostly they will love it.