Paul Graham is a renowned American computer scientist, entrepreneur, angel investor, and author. He co-founded the first web-based application spam filter, called ViaWeb, which was later acquired by Yahoo! in 1998. He founded Y Combinator in 2005, which quickly became the world's most successful startup accelerator, helping to launch major companies like Dropbox, Airbnb, and Reddit. Graham is an advocate for innovation, startups, and creativity, and has published many essays and books covering topics such as programming, entrepreneurship, and life philosophy.