This is where you'll find the majority of finishing kit for your bike. Front end stuff, seat post stuff and pedals. Cockpit and finishing kit is where you can really put the personal touch into your bike build.
Chances are some of the components that your bike came supplied with aren't exactly to your specification or taste. You may want to try a wider bar, with a shallower drop. You might be thinking of switching to a different type of clipless pedal. You can tweak the pedalling efficiency of your bike by swapping to a seat post with less layback. Then there's the jewellery opportunities of upgrading to a shiny new headset or slapping on some fresh new bar tape. And let's not forget the seemingly endless earch for The Perfect Saddle!