The main idea of:
It is usually written as a single declarative sentence.
In some cases it is implied rather than explicitly stated.
The following paper types require a thesis statement:
Analytical Paper: Breaks down an issue or an idea into its component parts, evaluates the issue or idea, and presents this breakdown and evaluation to the audience.
Expository (or Explanatory) Paper: Explains something to the audience.
Argumentative Paper: Makes a claim about a topic and justifies this claim with specific evidence. The claim could be an opinion, a policy proposal, an evaluation, a cause-and-effect statement, or an interpretation. The goal of the argumentative paper is to convince the audience that the claim is true based on the evidence provided.
Source: Purdue Owl