These are applications designed and distributed by Google, including core Android apps, such as the Play Store.
It includes applications which people have come to associate with Android devices, such as the GMail application, Google Maps, Navigation, Google Talk, Car Dock, Google Account Syncing (including Picasa / Contact / Calendar sync), Google Voice, Street View, Youtube, Voice Search as well as the big kahuna, the official Android Marketplace.
Note: Android Marketplace has since been replaced by the Play Store.
Where to find GApps?
First you need to know that the version of GApps you install to your device must correspond to the Android version running on your device – or you will experience force-closes and other nasty things. There are some sources you can check to make sure catching the right package:
- CyanogenMod GApps page
- XDA GApps collection
- TeamAndroid's GApps list (looks like an improved version of CM's, as it lists the Android version and some other details along)