Injectors are devices used to introduce a substance, typically a liquid, into another system. They are commonly found in various applications, such as in automotive engines, where they inject fuel into the combustion chamber to ensure efficient operation. Injectors can also be used in medical settings to deliver medications or vaccines directly into the body. In the context of automotive technology, fuel injectors replace older carburetor systems, providing better fuel efficiency and reduced emissions. In medicine, injectors can be manual or automatic, allowing for precise dosage and minimizing discomfort during administration.