Rash is a broad term for a wide variety of skin conditions. A rash refers to a change that affects the skin. Rashes can appear in many different ways ranging from red patches, to bumps and blisters. Rashes can be infectious or non-infectious and acute or chronic. The majority of rashes are harmless but it is important to understand what may be causing the rash. In evaluating a rash it is also important for your doctor to understand what other medical conditions you have that may or may not be influencing or causing the rash.