Do you have any steel in your home? You might think that you don’t, but there is almost always going to be some kind of steel involved in a building. Whether it is the rebar inside of cement, nails & screws holding things together, or a metal roof, you will have elements of your home that are vulnerable to rust. This means that you should be careful that this weakness doesn’t cause serious issues.
Rust is created when metals are exposed to water and oxygen through a process called oxidation. The damage rust causes is exponential, since it forms a porous material that can collect more water and damage underlying layers of metal. This is why rust should be treated as soon as possible to prevent it from doing further damage.
In some cases, rust is only going to be causing cosmetical damage, but it could also cause serious structural problems if it forms in the wrong place.