Search engine optimization for YouTube is the ever-evolving practice of optimizing YouTube videos, titles, descriptions, and more to rank well in YouTube's internal search engine and Google as a whole. Best practices include adding key terms to titles and descriptions, finding the optimal video length, promoting your videos on other channels, and paying attention to your metrics. 

Search engine optimization is the process of improving the quality and quantity of website traffic to a website or a web page from search engines. SEO targets unpaid traffic rather than direct traffic or paid traffic.