SLR - A single reflex cameras use a mirror between the lens and film to show a focus screen. The image in the viewfinder is the same as what appears as the image.
TLR - Twin reflex camera has 2 lenses with the same focal length.
Lens - Focuses on the image you want. Bends light to help to take pictures
Shutter - temporarily opens part of a camera to let light in when a photo is being taken
Shutter speed control - Length of time light is let into the camera
Aperture / Lens - Whole in the lens where light travels in the camera body
ASA/ISO/Film Speed - Measures sensitivity of an image. Brightens or darkens a photo