css round corner what is -moz-, -webkit-

[html]
.box {
  -moz-border-radius: 15px;
  -webkit-border-radius: 15px;
  border-radius: 15px;
 
  -moz-box-shadow: 10px 10px 20px #000;
  -webkit-box-shadow: 10px 10px 20px #000;
  box-shadow: 10px 10px 20px #000;
}
[/html]

-moz- –> firefox 1.0
-webkit- –> safari 0.2 and chrome 3.0
border-radius –> opera 10.5, IE9, Firefox, Chrome

more detail in developer.mozilla

IE condition

Note the special syntax:
!: not
It: less than
lte: less than or equal to
gt: greater than
gte: greater than or equal to

[html]
<!–[if !IE]>
Other than IE condition status<br />
<![endif]–>

<!–[if IE 6]>
Only IE 6<br />
<![endif]–>

<!–[if gt IE 6]>
IE 7 and higher<br />
<![endif]–>

<!–[if gte IE 8]>
IE 8 or higher<br />
<![endif]–>

<!–[if lt IE 9]>
IE 8 and below<br />
<![endif]–>

<!–[if lte IE 7]>
IE 7 or lower<br />
<![endif]–>
[/html]