android:id was added in API Level 1
This is a unique identifier name for the TextView, so you can refer to the TextView later in your project.
1. Add a TextView in your main.xml file.
2. In the main.xml file, add the code below.
<TextView
...
android:id = "@+id/myTextView"
/>
3. The "+" character is required if you have not yet defined that id, if perhaps the element you reference is lower in the .xml file.
Otherwise you if it's already defined above (or included) then you can omit the "+" char:
4. Compile and run!
Next Recommended Article: findViewById - Find a TextView using ID
Resources:http://developer.android.com/reference/android/view/View.html#attr_android:id
http://developer.android.com/reference/android/R.attr.html#id
http://android-wtf.com/2012/11/difference-between-at-plus-id-and-at-id-in-android/
http://stackoverflow.com/questions/5025910/difference-between-id-and-id-in-android
http://stackoverflow.com/questions/5048586/can-you-set-tab-order-in-xml-layout