Blonde Girl Wearing Black Stockings Outside At The Wall

Another common usage is as a communal surface to write upon. For instance the social networking site Facebook uses a wall to log the scrawls of friends. Users have gone on to create more advanced versions of the original wall, such as the application SuperWall.
Physiological wall
In marathon running a runner can 'hit' 'the wall'. A point where the human brain and body feels like it cannot be pushed further or continue. Runners find this incredibly hard to break through and continue.