What's a vendor? Well that's anyone who serves your customers. It includes hardware, software, and service providers such as HP, Cisco, Microsoft, Adobe, or Intermedia. Some of these will represent products you sold the clients. But it also includes things they bought on their own, such as a line of business application.
Vendor management means you take care of the relationship between your client and those vendors. It includes registering hardware, software, and services in a way that allows you to provide excellent service.
It also means you do all the talking. In other words, you translate from client (business talk) to vendor (tech talk). That's true during technical support, but it's also handy when discussing upgrades and choosing new products.
Perhaps the most important thing you can do with vendor products and services is to document them properly. I don't mean to provide alternative instructions (although that's useful), but to document where the code is stored, how it's registered, where services are located, passwords, and client-specific configuration information.
The video includes more tips as well. View it. Like it. Share it.