Service?

At one time in my life, I thought I had a handle on the meaning of the word "service". The act of doing things for other people. Then I heard the terms: Internal Revenue Service, Postal Service, Civil Service, Telephone Service, Service Stations, Customer Service, City/County Public Service. And I became confused about the word "service". This is not what I thought "service" meant. Then one day, I overheard two farmers talking, and one of them mentioned that he was having a bull service a few of his cows. SHAZAM! It all came into perspective. Now I understand what all those "service" agencies are doing to us...