Editing Hexadecimal (section)

==Base16 (transfer encoding)==
'''Base16''' (as a proper name without a space) can also refer to a [[binary to text encoding]] belonging to the same family as [[Base32]], [[Base58]], and [[Base64]].

In this case, data is broken into 4-bit sequences, and each value (between 0 and 15 inclusively) is encoded using one of 16 symbols from the [[ASCII]] character set. Although any 16 symbols from the ASCII character set can be used, in practice, the ASCII digits "0"–"9" and the letters "A"–"F" (or the lowercase "a"–"f") are always chosen in order to align with standard written notation for hexadecimal numbers.

There are several advantages of Base16 encoding:
* Most programming languages already have facilities to parse ASCII-encoded hexadecimal
* Being exactly half a byte, 4-bits is easier to process than the 5 or 6 bits of Base32 and Base64 respectively
* The symbols 0–9 and A–F are universal in hexadecimal notation, so it is easily understood at a glance without needing to rely on a symbol lookup table.
* Many CPU architectures have dedicated instructions that allow access to a half-byte (otherwise known as a "[[nibble]]"), making it more efficient in hardware than Base32 and Base64

The main disadvantages of Base16 encoding are:
* Space efficiency is only 50%, since each 4-bit value from the original data will be encoded as an 8-bit byte. In contrast, Base32 and Base64 encodings have a space efficiency of 63% and 75% respectively.
* Possible added complexity of having to accept both uppercase and lowercase letters

Support for Base16 encoding is ubiquitous in modern computing. It is the basis for the [[World Wide Web Consortium|W3C]] standard for [[Percent-encoding|URL percent encoding]], where a character is replaced with a percent sign "%" and its Base16-encoded form. Most modern programming languages directly include support for formatting and parsing Base16-encoded numbers.