This is an extract from wikipedia.
The D90 is a digital single-lens reflex camera model announced by Nikon on August 27, 2008. It is an advanced amateur model meant as a replacement for the Nikon D80. Nikon’s estimated retail price is $999.95 US for the body only. It is also available with the newly announced Nikkor AF-S DX 18-105mm f/3.5-5.6G ED VR kit lens for $1299.99. The lens by itself will sell for $399.95.
Some of the improvements the D90 offers over the D80 include 12.3 megapixel resolution and live view capability. The D90 is also notable for being the first DSLR to offer video recording, with the ability to record HD 720p videos, with mono sound, at 24 frames per second (for up to 5 minutes or 20 minutes for smaller videos).
* Nikon’s 12.3-megapixel Nikon DX format CMOS sensor.
* Movie function (D-Movie Mode).
* Active D-Lighting (4 levels and Auto).
* 3-inch TFT LCD with 920,000-dot resolution (VGA) and 170-degree ultra-wide viewing angle.
* Live View shooting mode (activated with a dedicated button).
* Continuous Drive up to 4.5 frames per second.
* 3D Color Matrix Metering II with Scene Recognition System.
* Multi-CAM 1000 autofocus sensor module with 11 AF points.
* ISO sensitivity 200 to 3200 (100-6400 with boost).
* Nikon F-mount lenses
* Built-in Sensor cleaning system (vibrating low-pass filter).
* HDMI HD video output
* Active Dust Removal System
* Support for GP-1 GPS unit.
* File formats: JPEG, NEF (Nikon’s RAW, 12-bit compressed), AVI (Moving JPEG).
* EN-EL3e Lithium-ion Battery, Battery Life (shots per charge) approx. : 850 shots (CIPA).
* Weight: Approx. 0.620 kg (without battery), 0.703 kg (with battery).
* ML-L3 Wireless (Infrared) remote control and MC-DC2 Remote Cord.
* MB-D80 Multi Power Battery grip.
* GP-1 GPS Unit (for GPS geotagging).
Nikon D90 was introduced as the first ever DSLR with video capabilities, being able to record HD 720p videos. Its CMOS sensor captures light in a form called rolling shutter.