A thesis is a one or two sentence statement that directly states what your paper is about. 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:
Transitions are visual cues that inform your reader where you are in your paper. Your thesis has already established the topics you will be covers in your compare/contrast paper so these cues help your reader know when you are moving on to a new topic.
For a large list of transition words, look at our transitions page.