When you sue a person, company, or the government, you must give notice to the other side that you have started the legal process. Or when you are already involved in a case and file papers with the court, you are required to give the other side notice of the paperwork that you have filed.
The legal way to give notice is to have the other side served with a copy of the paperwork that you filed with the court. This is called service of process.
Service of process means that the other side must get copies of any papers that you file with the court. In service of process, a third person (NOT you) is the one who actually delivers the paperwork to the other person or people involved in the case. The person who gives copies of court papers on your behalf is called a server or process server.
Until the other side has been properly served, the judge cannot make any permanent orders or judgments.