Dalvik is the managed runtime used by applications and some system services on Android. Dalvik was originally created specifically for the Android project.
Much of the documentation in this directory is intended to help with the ongoing development of Dalvik, as opposed to most of the other documentation on this site, which is geared more towards application development.
Please note, in Android 4.4 a new virtual machine - ART - is being introduced experimentally that will eventually replace Dalvik. Please see Introducing ART for details.