The user needs to be able to navigate up (towards the root page) and have an understanding of where she is in relation to the rest of the site.
The name breadcrumbs is probably a misnomer. Since it invokes the thought of Hansel & Gretel leaving breadcrumbs so that they could return the exact way they came. This pattern is more like a homeward path. It doesn’t capture the trail of your path but instead it marks the path from home to wherever you might be currently be in the site hierarchy. Even with the misnomer, we felt it best to stick with the terminology that was commonly used.
The pattern can be found at: Breadcrumbs.