Bit depth

Bit(binary digit) is the basic unit of information in computing and telecommunications.
The origin on the word ‘bit’ is attributed to john w. Turkey, who who had first written it on a bell labs memo on 9^th january in which he contracted ‘binary digit’ to simply ‘bit’.
In computing, a bit only has two possible values : 0 or 1, yes or no, true or false, + or -, etc.

Bit was also a character in the movie tron – which was only capable of providing yes or no answers. When answering yes it changed yellow[octahedron]/ when no it changed into a spiky red shape[35^th stellation of the icosahedron].

Bytes or multiples of e.g Megabyte, are used to specify the capacity of storage units and sizes of files. Files- Bytes, Hard Drives etc- Bytes.
Modern storage/peripheral devices are to manipulate data in whole bytes rather than individual bits.

A Byte is a group of 8 bits.
Historically, a byte was the number of bits used to encode a character of text in the computer, which depended on computer hardware architecture; but today it almost always means 8 bits – that is, an octect.

2 bytes or multiples therof are almost always used to specify the sizes of computer files and the capacity of storage units. Most modern computer and peripheral are devices designed to manipulate data in whole bytes or groups of bytes rather than individual bits.

Nibble.

A group of four bits or half a byte is sometimes called a nibble or nybble.
Nibbles Are practically obsolete these days.
Computer numbering formats
The amount of possible combinations doubles with each binary digit added – 1 byte(8 bits) has 256 possible values.
Every time a bit is added, the potential number doubles, eg 1, 2, 4, 8.

Bit depth

Bit depth specifies how much colour information is available for each pixel in an image. The more bits of information per pixel, the more available colours and more accurate colour representation.
There are only 2 possible values, black and white when an image has a bit depth of 1. An image with a bit depth of 8 has 256 values and so on for larger bits of depths. A grayscale image with a bit depth of 8, has 256 possible colours, 256 shades of grey including black and white. RGB is made of 3 colours, red, green and blue and has 256 possible values for each channel, this means it has over 6 million possible values.
HDR imaging, a new form of trying to get near to what the human eye can see. It compresses many photos, normally 20 or more, into one photo. 3 Colour channels, Red, Green and Blue, this makes White. Each channel has the potential for 256 values. 256 x 256 x 256= 16 million 77 thousand and two hundred and sixteen values= which gives over 16 million values/ranges of colour. RGB images with 8 bits per channel (Bpc) are sometimes called 24 bit images (8 bits x 3 channels = 24 bits of data for each pixel).