Display : block will take the whole line i.e without line break
Display :inline will take only exact space that it requires.
#block
{
display : block;
background-color:red;
border:1px solid;
}
#inline
{
display : inline;
background-color:red;
border:1px solid;
}
You can refer example in this fiddle http://jsfiddle.net/RJXZM/1/.