libguestfs is a set of tools for accessing and modifying virtual machine (VM) disk images. You can use this to inject files, resize, rescue, create, view or audit disks. libguestfs is also a library that you can link to management programs written in C, Perl, Python, Ruby, Java and other languages. In this talk, Richard Jones will introduce the tools and give live demonstrations. He also talks about how they work behind the scenes.