ISO : The lower the sensitivity, the finer the grain, but more light is needed. This is excellent for outdoor photography, but for low-light conditions or action photography (where fast shutterspeeds are needed), more sensitive or "fast" film is used which is more "grainy"

Aperture: Aperture is also known as 'f-stop' and you can think of it as being similar to the pupils in your eyes

Shutter speed: Shutter speed is how long the sensor in your camera is exposed to light

Sensor size: The three most common sensor sizes are full frame (the sensor is the same size as a frame of 35mm film), APS-C (is by far the most common format) and Four-thirds

Type of lenses

- Wide angle: 28mm or less, good for interiors and landscapes
- Standard: from 35mm and 85mm, good for general use and portraits
- Telephoto: from 100mm to 300mm, good for sports, portraits and wildlife

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References:
http://www.dpreview.com/∞
http://www.knowyourdslr.com/dslrbasics/startersguides/12708/dslr_starters_guides_aperture.html∞