Your knife is made from high carbon steel, 1095, 1084, 1075, 80CrV2 and such.  The advantage of high carbon steel is that it will keep and hold an edge better than stainless steel.  The disadvantage is that it can rust.  Keep your knife dry when stored. Do not clean you knife in the dishwasher.  This can damage the handle material.  If you are storing your knife for more than a few weeks, remove it from the sheath.  The chemicals in the tanned leather will cause corrosion.

Rust, which is iron oxide, can pit and damage blades. It is that orange/red color that you are familiar with. The chemical make-up is Fe2O3.

Now there is another type of iron oxide, Fe3O4, which is also known as patina.  Instead of orange/red it is more of a black/gray in color. The good news is that patina actually protects the blade from rusting.

Under normally conditions, cutting, washing, drying, over and over the patina will develop over time and you will end up with a very nice looking finish that will be protected from rust.