Topic = What is being discussed or written about. It is often a question to answer.

Claim = The answer to the question of the topic

Thesis statement = A statement of intention and purpose, expressing the central idea of an essay.

-- Adapted from Writing from Sources (8th edition) by Brenda Spatt

Let's define a little here:

• A claim is any sentence/statement that asserts something that may be true or false and so needs support:
  • Example: The world's temperature is rising.

• A main claim or thesis statement is the sentence that your whole essay supports. If you wrote a report to prove that the world's temperature is rising, the sentence stating that would be its main claim.

A thesis statement will be a broad statement, worth defending, that defines the scope and limits of the essay.

1. The thesis will be a substantial generalization that can stand by itself. It should answer, not ask, a question.

Examples of topics, not theses: 

• Who should go to college?
• How can students succeed in college?

Thesis:

• Only students who will make the fullest use of their education should go to college.

2. The thesis will be broad enough and arguable enough to be worth defending. It will not be an obvious truth.

• Too obvious: Poorly prepared students can find college work difficult.
• Too narrow: Some of the students in my history course found the second assignment too difficult.
• Thesis: To help unprepared students succeed, colleges should provide a full range of support services.
• Thesis: Since college can be difficult for poorly prepared students, admission should depend on the applicant's meeting certain standards of achievement.

3. The thesis will define the scope and limits of the essay. The author should stay within the boundaries of the thesis and not digress into other topics.

• Too narrow: Employment discrimination arises from an overemphasis on college degrees.
• Too broad: College is wasted on the young.
• Thesis: Regarding the college degree as a prerequisite for a good job and a better life can only discourage a fair and efficient system of employment and subvert the true purpose of higher education.

Adapted from Writing from Sources (8th edition) by Brenda Spatt