Intens can be used to perform an operation between different applications or activities.
It is basically a passive data structure holding an abstract description of an action to be performed.
package name and class name can specify the intent target, but you can also leave them null and define a category instead to let the user choose an application of that categoy.
If you expect a callback you have to pass the
-1: operation succeeded
1: user-defined activity results
0: operation canceled
You can find some common used examples for that in the DroidScript Wiki
For more information visit the Android Developer Page. There you can find informations about the activity, category and extra.
See Also: GetIntent