Reach schools are more selective, match universities are likely to admit you, and safety schools are where your credentials exceed requirements.

Think of it this way, the acceptance for: 

Reach = <20%
Target = 20-50%
Safety = > 50%

The Reach, Safety, Target is common approach used to help students create their college lists, just be aware of
how many of the universities you apply to fall in each. Ideally, aim for at least 4 Safety schools.