LCD and Viewfinder
Nikon D90 has a Fixed Type 3" LCD screen with a resolution of 920k dots. Both the screen size and the screen resolution is up to the standards of this class.
D90 has a built-in Optical (pentaprism) viewfinder. The viewfinder has a coverage of 96% and a magnification ratio of 0.64x. 96% coverage means that what you see in your viewfinder while shooting will slightly be different from the actual image.
Max Shutter speed
Nikon D90 can shoot continuously at max speed of 4.5 fps
and has max shutter speed of 1/4000 sec
D90 has a built-in flash, and it also has a flash shoe to mount your external flashes too.
Nikon D90 features both Contrast Detection and Phase Detection autofocus (AF) systems which ensures speed and accuracy of focusing in most situations. The AF system has 11 points to choose from. Nikon D90 also features Face detection AF
where it intelligently detects the faces in the frame and locks the focus automatically.
With Nikon D90, you can record your videos at a highest resolution of 1280 x 720 at 24 fps and save in and Motion JPEG formats. 1280 x 720 is a low video resolution by todays standards. If video quality is important for you, we recommend you to look at cameras with Full HD, even better 4K / Ultra-HD resolution
D90 has a built-in Mono microphone but no speaker.
Nikon D90 doesn't have any connections for external microphones and headphones. If you need a DSLR camera with external microphone connectivity, consider Pentax K-1 Mark II or Nikon D750 in a similar price range.
Connectivity and Storage
You can connect D90 to compatible devices via its HDMI port or USB 2.0 (480 Mbit/sec) port.
Nikon D90 is powered by battery which provides a shooting life of 850 according to CIPA standards.
Considering that the average battery life of DSLR type cameras is 883 shots, its battery life is about average in its class but it would still be wise to invest in some spare batteries for long photo trips.
Battery Life Comparison in Semi-Pro DSLR Cameras
Nikon D850 with its 1840shots is the model with longest battery life among Semi-Pro DSLR cameras. Check the comparison of Nikon D90 vs Nikon D850 or take a look at Longest Battery Life DSLR cameras list.
Nikon D90 Features Compared to Main Competitors
You can download Nikon D90's User Manual here