Web technologies are evolving at a rapid pace and so is Nginx. Upgrading server-side software can be tricky, especially if the server is currently in use. If you have a web farm, you might not feel comfortable with the idea of upgrading the web servers while the visitors are still connected to it. However, with upgrades you get new features and bug fixes, and quite often the pain of upgrading is worth the effort. In this chapter you will learn about upgrading your web server in ways that shorten or remove the downtime. You will learn about the options available to you so that you can exercise them in different scenarios.