People know a lot of stuff, but as it turns out it's kind of tricky to talk about what "knowing stuff" really means. A common framework for thinking about knowledge is the "DIKW" pyramid - Data, Information, Knowledge, Wisdom.
We start with data. *Data* is an abstracted, symbolic representation of... something. Like this:
0110100001100101011011000110110001101111
Data by itself isn't all that helpful. Sometimes we can infer or guess what data means based on where we found it or patterns that we've noticed, but that's not always the best idea. One way of adding meaning is adding metadata - data describing other data - like headings on a table, for example. Especially when it comes to data on computers, that binary data is usually constructed from some sort of standard or protocol so that other programs & computers will be able to interpret it later. So, according to the ASCII text encoding standard, the above string of 1s and 0s represents the word "hello".
We call a system for storing raw data a database. There are a bunch of different computer database systems out there, or you can make your own with a text editor or spreadsheet software. You can also have real-world databases - think old-school library card catalogs or giant collections of filing cabinets full of business records.
(and yes, for the pedants out there, 'data' is technically the plural of 'datum' - but most normal folks treat 'data' as a singular thing)
Once we have data, we can label, assemble, filter, and summarize that data to give it purpose and meaning to form information. For example, we can store data in a database to record how many widgets a company sells each day, but we can design an information system to read the data from the database and produce some more useful stuff, like how much money we should have made from those sales, how many widgets we should still have on the shelf, and what our historical sales trends look like.
Most database software systems are also fairly functional, though not incredibly user-friendly, information systems. Typically, when I'm talking about an information system, I'm talking about a piece of software designed to read from a database (or, maybe multiple databases - a data warehouse or data lake) and provide a simple, graphical interface for creating, reading, updating, and deleting data - a pattern often referred to as "CRUD". Physical, real-world information systems tend to be much simpler than their computerized counterparts - organizing post-it notes on a wall or index cards in drawers, for example.
Most people are pretty clear on the difference between data and information, but things start getting a little fuzzier as we move up to knowledge. Knowledge tends to be described as the application of patterns in information, or the linking of multiple pieces of information to form a contextual understanding of a situation in order to make decisions or take actions. I also like Chaim Zins' definition - knowledge is "a thought in an individual's mind, which is characterized by the individual's justifiable belief that it is true."
For example, information is knowing that we've sold 1000 widgets every week for the past 3 months, knowledge is knowing that our customers don't do much shopping outside of those 3 months, and that we probably shouldn't go buy a bunch of widget parts that we won't be able to sell until next year.
Knowledge is often tacit - it's hard to write down or communicate to other people. It's often personal, contextual, and experiential. It's also often shared socially - through conversations, stories, mentorship, and collaboration. Knowledge management is a whole field of study dedicated to understanding how knowledge is created, shared, and utilized within organizations.
And then there's wisdom. Wisdom tends to be understood as the ability to make sound judgments and decisions based on knowledge. It's often associated with qualities like insight, foresight, and ethical reasoning.