You’ve been sued when someone has filed a complaint with the court. In order for the lawsuit to properly begin, you have to be “served” with the complaint.
Being served means that you got “official” notice of the lawsuit. I’ll talk about the different types of proper service in another post.
Keep in mind that each court has its own rules about what exactly needs to happen to start a lawsuit — the things I talk about below are general rules, but your state might tweak them slightly. Also, some types of lawsuits, such as restraining orders or protection from abuse order, can start before you actually get notice of them.
You can tell it’s a complaint because at the top of the first page, it will have the name of a court (as in “In the Circuit Court of the State of Oregon for the County of Multnomah), the name of the person suing you and your name.
Usually, the complaint will have something called a “summons.”
This paper is usually in front of the complaint and tells you you’re being sued, tells you that you should respond within a specific period of time, and gives you information about getting an attorney — usually the number of the state bar’s referral service and/or legal aid.
If you get a letter from an attorney threatening to take legal action against you, that doesn’t mean you’ve been sued. You might be, but the letter isn’t enough to start a lawsuit.