Knowledge falls into two main types: explicit knowledge that can be written down, and tacit knowledge: that can only be learnt from experience, perhaps from tens of thousands of hours of experience.
Relaying explicit knowledge, passing it from person to person, from generation to generation, is not unique to humans, but in such abundance is a crucial difference.
In IT it is critical to record processes, to provide in-line help in software, and more detailed knowledge base information for power users.
Here's an example:
One day the Infrastructure Manager was 'fighting a fire'; their number two was fighting another fire; so was I: the need for another emergency change arose. I made the decision to pass the relevant protocol to the novice on my team, the only person available at the time: "Follow this as best you can and ask me when you're not sure". They did the job perfectly, no QA push-back, and didn't ask for any help. Without that written protocol, the fourth emergency change would have needed to wait.
Documentation of business processes adds value to the business. Documentation can be writen text, flow charts or pictorial representations.