IIS Express is a version of IIS optimized to ease website development. Among other features, it is self-contained, and lighter weight than the full version of IIS, and does not need to be run as a service, or require administrative rights for most of its functions.
IIS Express is a version of IIS optimized to ease website development. Among other features, it is self-contained, and lighterweight than the full version of IIS, and does not need to be run as a service, or require administrative rights for most of its functions.
More information can be found here, the official Introduction to IIS Express page.