Wherever there is metal, water and air together, there is a chance that the metal will start to rust. While this is a natural process, it could be a major concern for a homeowner. While rust might just be a cosmetic problem, other times it could pose a danger. For example, if you have an electrical panel that has a lot of rust on it, that could cause a fire. If that is the case for you, you need to have an electrician take a look at it as soon as possible. If the rebar inside of cement fixtures of your home starts to rust, that could cause structural issues. The issue will just get worse the longer it is left untreated, since the rusting rebar will expand, causing the cement to crack and expose more rebar to the elements.
Rust removal is a meticulous process, since leaving any trace of rust behind will make it so the problem will resurface again. Just painting over the rust will not help, since the rust will keep spreading underneath the paint.