Suppose you've had a good night out at the pub and now it's time to leave. You step out of the pub full of high spirits, all ready for the long and weary trek home, but find that your balance is mightily affected by your libations. Each step you take seems to be randomly selected from left, right, backwards or forwards. You are experiencing a Drunkard's Walk.

The good news is that given an infinite number of steps, you are guaranteed to come across your home at some stage (i.e. the probability of finding your house tends to 1 as the number of steps tends to infinity). It is worth noting that if you were doing a Drunkard's Walk in three dimensions, (i.e. at each step you could either go left, right, backwards, forwards, up or down) then you would no longer have this guarantee. In this case the average probability of reaching any particular point is about 0.6.