What's the difference between these selectors?

Hi Alfons,

• :nth-child takes an integer value that allows you to select a child element. For example, if you have a <ul> with list items and you want to only select the 3rd item, you can do it with :nth-child instead of applying a class or ID to the 3rd item. Here's an example on CodePen that shows this in action: http://codepen.io/nickpettit/pen/FnejA
• :first-of-type is a little tricky to explain in words, but it matches the first element that is of the type described in the selector. For example, if there were several nested <section> elements that also had siblings of other types, and you just wanted to select the first <section> (and not the first element) then you want :first-of-type. Here's an example on CodePen: http://codepen.io/nickpettit/pen/wiGrq
• :only-of-type is similar to the previous example, except it will select elements only if they have no other similar siblings. Here's the same example in CodePen: http://codepen.io/nickpettit/pen/xKHdf - In this example, try changing header to section, and you'll see that it doesn't select the section elements. That's because there are multiples. However, there's only one header.

I hope that helps!