A thesis is the central idea of a piece of writing with the entire work developing and supporting the idea. Though sometimes unstated, a thesis should always govern a paper. It usually appears as a thesis statement somewhere in the paper, primarily in the opening paragraph.
This resource from the Online Writing Lab at Purdue University provides tips for creating a thesis statement and examples of different types of thesis statements.
This handout describes what a thesis statement is, how thesis statements work in your writing, and how you can discover or refine one for your draft.
A Helpful Video from ETSU