How does CSS clearing really work?

Question

I have a

that I want to be on a line by itself. According to W3Schools, this rule:

div.foo {
  clear: both;
}

...s

Answer 1

I generally do the following for that effect:

float: left;
clear: right;

I don't know if it applies merely to the element to which it is applied, though it makes sense.

The specs are available here, though: http://www.w3.org/TR/REC-CSS2/