How to create an external intent to an application?

I have 3 related questions that can all be answered together:

1. How can I check the applications installed on the clients device?

2. How can I create an int开发者_如何转开发ent to an application (ex. Maps, SMS, Facebook, Words With Friends, etc.)?

3. How can I create a specific intent for the dictionary.com app that lets me search for a word?

here are some of the answers you seek .... tada :

1 - List installed application : http://smartandroidians.blogspot.com/2010/07/getting-list-of-installed-application.html

2 - new intent for default sms application : launch sms application with an intent

3 - i'm not sure but this could help Using Intent in an Android application to show another activity