Knowledge is any concept that exists.
Human knowledge is any concept that has been thought by at least one human.
Generally, the more humans who agree with a concept, the more the concept is seen as true by humankind.
Knowledge can be stored in infinite ways. It can be stored as words on paper, drawing on canvas, neural state in a brain, bits in a database, rings of a tree, and more.
Knowledge of the world we can observe via human senses and believable tools is captured well via scientific methods.
Knowledge touches on truth.