In 3D engines like Unity or Unreal, the computer doesn't "see" a chair; it sees a list of thousands of vertex positions (vectors). When you turn the camera, the engine applies a to every single one of those vectors simultaneously to calculate where they should appear on your 2D screen. The Takeaway
Vectors are the (the points and directions), and Matrices are the "How" (how those points change). Mastering the relationship between the two is the first step toward building anything in 3D.
The Building Blocks of the 3rd Dimension: Vectors and Matrices
This creates a new vector that is perfectly perpendicular to two others. It’s the "secret sauce" for finding which way a flat surface is facing. 2. Matrices: The Transformation Grid