There are millions of possible objects that can be described in science, too many to create common names for every one. As a response, a number of systems of systematic names have been created.
These can be as simple as assigning a prefix and a number to each object (in which case they are a type of numbering scheme), or as complex as encoding the complete structure of the object in the name. Many systems combine some information about the named object with an extra sequence number to make it into a unique identifier.
Systematic names often co-exist with earlier common names assigned before the creation of any systematic naming system. For example, many common chemicals are still referred to by their common names, even by chemists.