A thesis statement is a sentence that directly states the central idea of your written assignment. In essays, a thesis statement is usually included in the introduction. In longer pieces of writing, it may appear further along, but still near the beginning.

A successful thesis has the following characteristics:

• it is interesting to the readers
• it is specific
• it narrows down the scope of the topic to "make it manageable"

Your thesis is generally one of the harder sentences to write, especially for those new to writing research papers.  You want the reader to know with this one statement what your stance on the topic is and what you intend to prove with your research.  Some good examples of a thesis statement would be:

• While cake and pie are both desserts, the structure, ingredients, and ease of transportation sets pie apart from its main competitor.
• An analysis of video game profit margins reveals one challenge facing game developers: the success of AAA games and the popularity of independent titles.
• In the movies Shaun of the Dead and 28 Days Later, the opening sequence establishes the tone and theme of the film through non-diegetic sound, methodical pacing, and striking visuals.

That's ok! As you develop your essay or research paper, your thesis may change. Revise it to reflect the scope and the central idea of your writing.

Writing evolves in stages; sometimes, you may not know what your thesis will be until you start to write. The concept of a working thesis is important here.

A working thesis should have two parts: a topic part, which states the topic, and a comment part, which makes an important point about the topic. 

Examples

• Topic: Cake and pie are both desserts but are very different
• Comment: pie is the clear winner because its better structured, has a bigger variety of fillings, and is much easier to take with you

• Topic: Difference in profit margins: AAA games vs Indie titles
• Comment: indie titles are growing in popularity and may make the smaller teams more money than what programmers get from AAA titles

• Topic: There were a lot of zombie movies in the 00s but only a handful really stick out as "noteworthy"
• Comment: Its not just about the tone of the movie, but how they pace it.  The sound and visuals have to be unique but not jarring or hokey.