Typically at the top of a screen, this is a chain of links the user has clicked to get where he is. If you have a lot of categories and subcategories of information or products on the site, these can help people navigate. Make sure they are actively linked so if a visitor clicks down three or four levels, he can back up a level or two very easily by clicking the link in the breadcrumb trail. Never rely on the online help to solve your users' problems. It is best to assume that users will never look at the help.
Clutter is bad.
When in doubt, err on the side of simplicity. A clean look and feel typically get much higher satisfaction scores than a crowded look with a lot of things going on. Some animation is good. Animated images and other techniques to add movement to the site can add to the users' enjoyment. Don't overdo it.