Dictionary.com defines "service" as an act of helpful activity. Further interpretation includes a supplier of utilities, such as water or electricity, and a provider of accommodation, such as a waiter or server.
The term "service" can also reference the military. To be in a branch of the armed forces is commonly cited as being in the service.
The phrase to "be at one's service" implies that a person or organization is ready to be of help to another whenever needed, such as a maid, servant, furnace repairman or humanitarian organization.
Derived from the Latin word "servitium," meaning "servitude," the common word "service" can be used as a noun, adjective or verb.