From left to right, each column is headed by a letter: B, I, N, G or O. The center spot (the third number down in the "N" column) is always given to the player, and often is marked "Free."
A generic bingo card could look like this:
| B | I | N | G | O |
| 14 | 16 | 44 | 59 | 62 |
| 3 | 20 | 34 | 55 | 70 |
| 11 | 30 | free | 46 | 74 |
| 8 | 24 | 40 | 50 | 67 |
| 5 | 17 | 36 | 54 | 72 |
One more thing: A bingo card's "B" column may only contain numbers from 1 to 15; the "I" column may only contain 16 to 30; the "N" column 31 to 45, the "G" column 46 to 60, and the "O" column 61-75. In other words...
B = 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 I = 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 N = 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 G = 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 O = 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75
Also: Bingo Lingo!