What's the difference between an id and a class?
css, html
Solution
`ids` must be unique where as `class` can be applied to many things. In CSS, `id`s look like `#elementID` and `class` elements look like `.someClass`
In general, use `id` whenever you want to refer to a specific element and `class` when you have a number of things that are all alike. For instance, common `id` elements are things like `header`, `footer`, `sidebar`. Common `class` elements are things like `highlight` or `external-link`.
It's a good idea to read up on the cascade and understand the precedence assigned to various selectors: http://www.w3.org/TR/CSS2/cascade.html
The most basic precedence you should understand, however, is that `id` selectors take precedence over `class` selectors. If you had this:
<p id="intro" class="foo">Hello!</p>
and:
#intro { color: red }
.foo { color: blue }
The text would be red because the `id` selector takes precedence over the `class` selector.
Problem
What's the difference between `<div class="">` and `<div id="">` when it comes to CSS? Is it alright to use `<div id="">`? I see different developers doing this in both ways, and since I'm self taught, I've never really figured it out.