You can quickly switch between the perspective and orthographic camera using the K or in the top toolbar by ticking Configuration - Preferences - Use perspective camera. Both cameras have their advantages and it’s beneficial to switch between them depending on your current needs.
Perspective camera (default)
The perspective camera gives you more information about depth, objects which are far away are smaller than those nearby. A perspective view is as seen by human eyes in the real world.
Orthographic camera
The orthographic camera is commonly used in engineering. All objects appear at the same scale, parallel lines remain parallel and a unit of length will appear to have the same length everywhere on the drawing. This makes it easier to judge relative sizes and to align models.