Jean-Paul Sartre was a French philosopher and writer who lived during the 20th century. He wrote books, plays, and essays and taught philosophy. His ideas were to help people think and understand the world around them. He believed that life should be lived without relying on other people or institutions like governments or religions. His idea was that everyone should take responsibility for their own decisions and behavior. In other words, we should be responsible for our own lives, instead of being controlled by others and doing what other people expect us to.