The collaboration between two or more brands. This collaboration is based on the co-product definition in a functional or a symbolic level on the one hand, and on the co-signature of the product by the partner brands on the other.
We must distinguish between:

The host-Brand : the brand originating from the product category where the co-branded product is launched. In the case of the shaver made by Philips / Nivea, the host-brand is Philips.
The guest-brand : the brand bringing symbolic values or/and a specific component to a co-branded product. For the Philips/Nivea electric shaver , Nivea is the guest-brand. For the LG/Prada mobile phone, Prada collaborates to design the product and is the guest-brand.