Shutter speed, it is the interval at which the shutter opens to allow a specific amount of light to penetrate through the lens and fall on the imaging sensor. Simply put, the longer the shutter allows light to shine through the lens, the brighter the picture. Have you ever wondered why of some the shots are darker than the others? That is because the shutter moves too fast that only allows a fraction of light penetrating through.
The duration that the shutter is opened is called the shutter speed. It is normally measured in 1/2second, 1/200 second, or even lesser. If a picture is too dark, just configure to slower shutter speed to allow more light. One might be confused with the indication of 1/2, 1/3200 and etc. Shutter speed of 1/2 is slower than 1 /200, that means picture that is taken with 1/ 2 is brighter than the one taken with 1 /200. That also means 1 /2 shutter speed needs steadier hands to hold the camera as a slight movement will potentially blur the shot. That is why people use tripods at night, as one might need slower shutter to capture enough light to get a clear picture.
Summary
Fast shutter speed = darker shot + less blur (sharper) + small fraction (1/400 , 1/1000)
Slow shutter speed = brighter shot + more blur + bigger fraction (1/2, 1/30)
Examples below (1/100 on the left image and 1/30 on the right image).
7th May 2015
Stanley Chuah