A measure in music notation (also called a bar) contains a certain number of beats as specified by the time signature. They are purely a conceptual way to divide the music into rhythmic, managable chunks. Each measure is indicated by two vertical bar-lines drawn completely through the staff or grand staff from the top line to the bottom one. For the computer-literate, you could loosely think of each note as a bit and each measure as a variable-length byte.

For instance, if the time signature is 4/4, then four quarter notes or their equivalent will reside in each measure. The following example has a staff with three measures in 4/4 time. The first measure has four quarter notes (one beat each), the second has two half notes (two beats each), and the third has one whole note (four beats).

```
/\
|----| /-------------------------------|------------|------|
|    |/                                |            |      |
|----/---------------------------------|------------|------|
|   /|       4    *     *     *    |*  |  |O    |O  |  O   |
|--/-|/\---------|-----|-----|-----|---|--|-----|---|------|
| |  |  |    4   |     |     |     |   |  |     |   |      |
|-| -|--|--------|-----|-----|-----|---|--|-----|---|------|
|  \ |  |        |     |     |     |   |  |     |   |      |
|---\|_/-------------------------------|------------|------|
|    |
|   \|
```

If a certain note's duration carries it beyond the end of a measure, two different notes at the same pitch are drawn in each measure and a tie is used to connect them.