In music notation, a slur resembles a parenthesis tipped on its side over the top of two or more notes. It looks identical to a tie except that a tie joins two identical notes, while a slur must span distinct notes. It indicates that the notes should be articulated smoothly together, with no or very little pause between them.
When drawn on the staff, it looks something like this (complete with time signature and a quarter note scale):
___
/\ ___ / ---___
---| /----------------___--- \----|----/----------\----||
|/ / \ | | \ ||
---/----------------/---------------|---|----|-----------||
/| 4 / | | | | * ||
-/-|/\------------/---------|----|--|---|----|---*---|---||
| | | 4 | | | | | * | | ||
|--|--|----------|-----|----|----|--|--*--------|----|---||
\ | | | | | * | | | ||
--\|_/-----------|-----|---*--------|-----------|--------||
| | *
\| -*--