What is the purpose of a thesis statement in an introduction?

The purpose of a thesis statement in an introduction is to make a specific claim and preview the content of the paper. A well-crafted thesis statement provides a clear and focused argument that guides the direction of the writing. It indicates to the reader what the main argument or point will be, allowing them to understand the scope and purpose of the ensuing discussion. By previewing the content, the thesis helps establish the organization of the paper and signals the key points that will be explored, making it easier for readers to follow the writer's reasoning.

The other options serve different functions in writing. Providing a definition of terms can help clarify specific concepts, but it does not encapsulate the main argument. Summarizing the main ideas is typically done in the conclusion rather than the introduction and lacks the specificity needed for a thesis. Comparing and contrasting different viewpoints is an analytical approach that may be part of the body of the paper but does not represent the function of a thesis statement, which is to assert a specific stance rather than merely compare perspectives.