18-200 is the zoom length from 18mm to 200mm
f3.5-5.6 is the aperture range where it is 
f3.5 at 18mm and f5.6 at 200mm
The codes below explain all the other letters 
G 
    IF ED AF-S DX VR
  
    | AF-S | Auto focus incorporating 
    Nikon's silent wave motor 
    (see SWM below). | 
  
    | ASP | Aspherical Lens Elements. A 
    type of lenses that virtually eliminates the problem of coma and other types 
    of lens aberration. The are particularly good at correcting distortion in 
    wide-angle lenses as well as contributing to a lighter and smaller lens 
    design. | 
  
    | CRC | Close Range Correction System. 
    Used in fisheye, wide-angle, Micro and selected medium telephoto Nikkor 
    lenses. It provides a focusing system which works well even at close 
    distances using lens elements configured in a 'floating element' design 
    which each one moves independently. | 
  
    | D | Distance information. D-type 
    Nikkor lenses relay subject to camera distance information to Nikon AF 
    camera bodies, which allows for 3D Matrix Metering and 3D multi-sensor 
    balanced fill flash. D-type lenses also have a manual aperture ring. | 
  
    | DC | Defocus-image Control 
    technology. Auto-focus DC Nikkor lenses alls the photographer to control the 
    spherical aberration in the foreground or background by rotating the lens DC 
    ring. It creates rounded out-of-focus blue that some portrait photographers 
    like to use. | 
  
    | DX | DX coded lenses are Nikon's 
    range of compact and lightweight digital-only lenses featuring a smaller 
    image circle that is optimised for use with the DX format image sensor. 
    Picture angle is approx. 1.5x focal length of a 35mm format equivalent and 
    they allow a greater wide-angle coverage. They can only be used on Nikon 
    Digital SLR's. Teleconverters cannot be used with DX lenses. If you put a DX 
    lens on to an FX camera for example the D3 it will drop into a DX crop 
    reducing the pixel count by more than half. | 
  
    | ED | Extra-low Dispersion. ED Glass 
    - an essential element of Nikkor lenses. Provides superior sharpness and 
    colour correction by effectively reducing chromatic aberration. Chromatic 
    aberration is what occurs when light rays of varying wavelengths pass 
    through optical glass. Nikon have developed several types of ED glass 
    suitable for various lenses which deliver stunning sharpness and contrast 
    even at their largest apertures. | 
  
    | G | Genesis.  G-type Nikkor 
    lenses relay subject to camera distance information to Nikon AF camera 
    bodies, which allows for 3D Matrix Metering and 3D multi-sensor balanced 
    fill flash. G-type lenses have no manual aperture ring. | 
  
    | IF | Internal Focusing. The lens is 
    able to focus without physically changing its size, where optical movement 
    is limited to the interior of the non-extending part of the lens barrel, 
    allowing for a more compact and lightweight lens as well as closer focusing 
    distances. | 
  
    | M/A | M/A Mode. Allows switching the 
    lens from Auto-focus to Manual focus with virtually no time lag. | 
  
    | Micro | Found on lenses for Macro 
    Photography of 1:1 ratio, life-size close-ups. Each lens offers stops down 
    to f/32, this permits maximum depth of field for close-up and macro 
    shooting. | 
  
    | N | Nano Crystal Coat an 
    anti-reflecting coating. It virtually eliminates internal lens element 
    reflections and reduces ghost and flare particular to ultra-wide zooms. | 
  
    | PC | Perspective Control. These 
    lenses are equipped with a tilt and shit mechanism that allows photographers 
    to manipulate image perspective, distortion and focus. They have 1:2 life 
    size macro capability. Ideal for commercial photographers who shoot table 
    top product photos, or building photography. | 
  
    | PC-E | New perspective control 
    lenses, we haven't yet worked out what the E stands for. | 
  
    | RF | Rear Focusing. A system were 
    all the lens elements are dividing into specific groups, with only the rear 
    group moving for focusing, making the auto-focus operation smoother and 
    faster. | 
  
    | SIC | Superior Integrated Coating. 
    This is a multilayer lens coating that helps reduce ghost and flare to a 
    negligible level, as well as minimising reflection in the wider wavelength 
    range and superior colour balance and reproduction. | 
  
    | SWM | Silent Wave Motor. This gives 
    lenses a quick, ultra-quiet focusing system. This system works by converting 
    travelling waves into rotational energy to focus the optics. This enables 
    high-speed auto focusing. | 
  
    | VR | Vibration Reduction. Nikon's 
    innovative system to minimise image blur caused by camera shake, and allows 
    shooting at a shutter speed 3 stops (eight times) faster. It enables 
    handheld shooting at dusk, at night, and even in poor light. It also detects 
    automatically when the photographer is panning. VR lenses have two angular 
    velocity sensors, one to detect  up-down motion  and the other to 
    left-right motion. Calculations are performed on the collected data and the 
    results are used to compute the target position to which the VR lens group 
    is moved. Voice-coil motors then move the VR lens group into that position. |