Simplify the following text for a Grade 12 native English-speaking person.
Original: California State University , Northridge ( also known as CSUN , Cal State Northridge ) is a public university in the San Fernando Valley below the Santa Susana Mountains , in the community of Northridge within the City of Los Angeles , County of Los Angeles , California , USA .
Simplified: California State University , Northridge or CSUN is a public university in the community of Northridge , California , USA .