Translations:Android Training/Building a Simple User Interface/16/en

From Android Wiki

android:layout_width and android:layout_height[edit source]

Instead of using specific sizes for the width and height, the "wrap_content" value specifies that the view should be only as big as needed to fit the contents of the view. If you were to instead use "match_parent", then the EditText element would fill the screen, because it would match the size of the parent LinearLayout. For more information, see the Layouts guide.