Read: This article is a solid overview of intents: http://www.vogella.com/tutorials/AndroidIntent/article.html. In particular, have a look at 1.4. Sending out explicit or implicit intents and 2.2. Example: Using the share intent. The article talks about many other powerful usages of intents that we will not be covering in detail, such as:

• Registering your activity so it can receive intents from other apps.
• Using intents to return data to the original activity.