What is a thesis statement?

A thesis statement serves as the central argument or claim of an essay or paper, clearly expressing the main purpose and guiding the direction of the writing. It typically encapsulates the writer's position on a topic while providing insight into how the paper will be structured or what themes will be explored. A well-crafted thesis statement articulates the writer’s stance and sets the stage for the supporting arguments that will follow, making it a crucial element for effective academic writing.

In contrast, a question that ignites discussion does not assert a specific viewpoint or argument, which is essential for a thesis statement. A summary of the conclusion, while important, does not reflect the initial claim; instead, it would come at the end of the paper. Lastly, a brief biography of the author is not relevant to the content or purpose of the paper itself, focusing instead on the writer rather than the argument being made. Therefore, identifying the thesis statement as the sentence that states the purpose of a paper captures its essential function in writing.