global variable

[bhuvaneshnick]

here board id global variable
Take the game board example from earlier—you might decide to create a function to display the board and have that function access a global variable. But what happens if you want to display some board other than the current board—for example, to show an alternative move? Your function doesn’t take the board as an argument; it shows only the single global board. Not very convenient!

could any one detial what is said here.it will be more good if you do with example code