Lev Vygotsky was a Russian psychologist born in 1896 who studied law at Moscow State University. He is known for developing cultural-historical psychology and coining the concept of the zone of proximal development, which refers to the difference between what a learner can do independently and what they can do with guidance and is considered an important aspect of learning. Vygotsky believed that learning precedes development and argued against using tests to measure intelligence alone.