Accepted Solutions is a method by which you identify and highlight the reply that best answers a question that you've posted. When you accept a solution, both the question and the solution get special icons and links that take you directly from the question to the answer. Read more

How do I mark a message as a solution?

To mark a message as a solution, click Accept as Solution on the reply. 

If you change your mind or if another reply provides an even better answer, you can revoke the first selection and accept the second reply.

To revoke an accepted solution, click Options > Not the Solution.

You can choose another solution or leave the question unsolved.