Nihilism is a very commonly misunderstood philosophy! Its often confused with Pessimism, and general negativety; however, this philosophys main proponent, Friedrich Nietzsche, argued about the concept of "meaning" and "truth" stating that there was no such with his most fundenmental explanation of this idea being highlighted in his most popular work Beyond Good and Evil. Here he criticizes and questions the existence of metaphysics, epistemology and the concept of knowledge, truth, and morals. He states that other philosopher whole point is to be critical of their surroundings, but they never question the most fundemental viewpoints that lay the foundation to each of their claims. For this reason he rags on may other philosopher like Epicurus and Kant, because if they were to truly question the nature of these concepts you would need to question there existance.