Accepted Solutions are a way to mark questions you have asked as solved. This is particularly important when you ask a question in the forum and a user takes the time to provide a very thorough response. Additionally, marking posts as having an Accepted Solution gives credit to the user that answered your question, and it helps other users quickly find the answer if they have the same or a similar question.
How to mark a post as an Accepted Solution?
To mark a post as an Accepted Solution, click on the "Accept as Solution" button next to the reply button. After you mark a reply as an accepted solution, the original post will be marked as solved and the response will be marked as the solution. Only the user who started a thread, the original poster, can accept a reply as the solution. You can also revoke an accepted solution, if a better answer is given, and apply the accepted solution to the new answer.