A thesis is a statement placed as a premise in an argument and it should sum up what the essay is about. A good thesis statement contains a part which the writer desires to argue and also states how it is going to be argued in a succinct manner. Usually the introduction is closed with the thesis statement in short essays. The thesis should not be a question or a list of facts but it should be a claim that could be argued. Further, it should be clear, specific and strong.
Example: “Green house effect and global warming should not be considered as serious issues.” This thesis is just an opinion, but not a debatable argument. Hence this is not a strong thesis.
On the other hand, the following thesis on the same topic provides a claim and argument.
Example: “Green house effect and global warming should not be considered the most significant issue of modern times because planet earth periodically undergoes cycles of cooling and warming from time immemorial and the spells of rising temperature are beyond human control since the changes are part of the natural cycle.”
A thesis should be concise since it is central to the whole essay and it should be defended with evidence. Moreover, it provides a quick preview of what the writer is going to say about the topic discussed and it organizes the building blocks to be used throughout the essay. The writer considers the thesis as a tool to maintain the focus on the topic and to provide the unifying thread to the argument. As for the reader, the thesis becomes a map and helps the reader to distinguish the main ideas and engages his/her attention to details. Therefore, a thesis should be debatable, apt and easily identifiable.