The Gettier problem is a philosophical issue that challenges the traditional definition of knowledge as justified true belief. According to this definition, for someone to know something, three conditions must be met: the belief must be true, the person must believe it, and there must be justification for that belief. However, Edmund Gettier, the philosopher who introduced this problem in 1963, presented scenarios where these conditions are satisfied, yet intuitively, the person does not truly "know" the information. These examples suggest that additional criteria are needed to fully understand the nature of knowledge.