Android developers have done wonders with these lock screen widgets, to a point where today they are used by a large portion of the Android community.
They first became available on the Android 1.5, and they've been getting more and more popular ever since with integrated weather and news information, as well as a lot of other, readily available data package. Android lock screen widgets are basically self-contained codes that can run a program, in the vast majority of the time also acting as shortcuts to certain apps.
