how does css clearing unequivocally work?

i have <div> i wish line itself. according , rule:

div.foo {
  clear: both;
}

...should meant this:

"no floating elements certified presumably left right side."

however, i boyant twin <div> elements left, ask order above initial one, second does budge.

on hand, i ask "clear: left" second <div>, moves down unbroken line. normal approach, nonetheless i don't know since i have this.

is w3schools outline above feeble stated, am i blank something? is clearing order wholly means pierce component applied?

answer

thanks michael s john d good explanations. warren separate , that's where i found answer (emphasis mine):

this ability indicates sides an element's box(es) competence adjacent an earlier floating box.

so: clear wholly affects position component applied, family elements seem before code.

disappointing i can't tell <div> divs pierce down, nonetheless them's breaks. :)