What thing in camera reduce noise? - 1

Usually i take pictures with my iphone 4s but the image it captures its so noisy so i decided to buy dslr camera so i want to know what thing reduce image noise and makes the image clean… What thing makes my 4s capture images so noisy? Is it for the low 8mp it has

Added (1). Please give me full detail not short answer

In photography circles phones are well known world wide as pure junk.

Buy a real camera, a dslr.

Photography is essentially the act of capturing light so the most important element in taking pictures is the light. The better the quality of light, the better the picture will be. The proper amount of light can be gauged through the use of the camera's lightmeter but assessment of the quality of light falls upon the shoulders of the photographer. The better a person can determine good light and adjust the camera to properly capture it, the better the photograph will be.

Noise is brought about by low light usually and is directly a product of high ISO values. The lower ISO is set, the more saturated colors will become. You can only use low ISO values when there's lots of light to work with. At this point, you should now understand that the thing that causes your images to be so noisy is you. Stop forcing the camera to shoot in low light. Either use flash or select a better lighted place to shoot pictures with.

Megapixels tell nothing but picture size. It has nothing to do with image quality although a larger picture can store more information that will help maintain a better image quality when printing pictures to gigantic sizes.