When was the last time someone told you that they were a salesperson? Probably not recently as salespeople now call themselves Account Managers. A job title is a term that describes in a few words or less the position held by an employee. Depending on the job, a job title can describe the level of the position or the responsibilities of the person holding the position. When you're looking for a new job it's important to use an appropriate job title on your cv. You really need to sell yourself to the person reviewing your application. Describing your job as "Internal Optimization Superhero" will definitely get their attention.