Business to business interactions or B2B is when businesses sell to businesses. It's a pretty common term as is Business to Consumer (B2C). Less common is G2B and G2C for Government to Business and Citizen/Consumer respectively. Sharing the terms tends to lead to sharing the same sort of paradigm thinking about the interaction. But these aren't the only combinations that are possible. Other possibilities are C2B, C2C, C2B, B2G, G2G and C2G. I started thinking about these less discussed terms when I read about a G2G experience that went horribly wrong and we ended up admitting Iraqi IED builders as refugees into the US because the fingerprint database proving they had waged war against us wasn't hooked up to the DHS systems for checking for excludable aliens.
So why do we find B2B and B2C very useful but not necessarily the other possibilities? Is it that those sorts of interactions don't happen? Hardly. C2B is also called the labor market and is huge. C2C is sometimes better known by its most famous participants, eBay and Craigslist. B2G is the traditional government contracting space.
Changing the label tends to change how you think about the interaction. Imagine if C2B interactions were thought of more like B2C. It's an interesting alternative view.