SproutLoud is an application that stores companies' marketing materials online, and companies can grant access to them by invitation. Learn more about SproutLoud
A SproutKey is a code that is needed to register for access to a company's marketing programs. All SproutKeys are case-sensitive.
The company that sent you an invitation is offering you access to their marketing programs.
Registration is free, but is by invitation only and requires a SproutKey.