internet-explorer - IE rendering mode

Question

I am a bit confused on how IE 9 and IE 10 decide to render

On one of my customers machine it was using IE 7 document mode and on another it was using standard mode.

Does the doctype affect how it renders?

Answer 1

The mode could be controlled by the X-UA-Compatible meta tag or HTTP response header:

<meta http-equiv="X-UA-Compatible" content="IE=9">

or if you want to render with the latest available mode you could use edge:

<meta http-equiv="X-UA-Compatible" content="IE=edge">