css selectors - What does a[href^="..."] do in CSS?

Question

I have used CSS before and I came across the below CSS style, don't have a clue what it does.

a[href^="http:"] {
   background: url(img/keys.gif) no-repeat right top;
}
a[href^="http://mysite.com"], a[href^="http://www.mysite.com"] {
   background-image: none; padding-right:0;
}

Answer 1

a[href^="http:"] 

Selects an <a> element whose href attribute value begins with http:.

For example:

p[title^="para"] {background: green;}

Will match the following:

<p title="paragraph"> This paragraph should have a green background. </p>