Blocks
From MoodleDocs
Note for Contributors
This page should explain briefly what blocks are.
On the left and right sides of the course homepage there are side blocks, which can be added, removed and moved around.
To enable arranging blocks (as well as the content of the course), editing should be enabled (click the "Turn editing on" button located in the top right corner of the screen).
See also
Developer documentation: A Step-by-step Guide To Creating Blocks