What is a character set in computing?
A character set is a collection of characters (letters, digits, symbols, control characters) that a computer can represent, each mapped to a unique numeric code.
What is a code point?
A code point is the numeric value assigned to a character in a character encoding, such as 65 for 'A' in ASCII.
What does ASCII stand for?
ASCII stands for American Standard Code for Information Interchange.
How many bits does ASCII use to represent each character?
ASCII uses 7 bits per character, allowing 128 different characters (27 = 128).
What is the range of ASCII code points?
ASCII code points range from 0 to 127, covering English letters, digits, punctuation, and control characters.
What is a major limitation of ASCII?
ASCII can only represent 128 characters, which is insufficient for languages with non-Latin scripts (e.g., Chinese, Arabic) and many symbols like emoji.
What is Unicode?
Unicode is a comprehensive character encoding standard that assigns a unique code point to virtually every character in all human languages, including emoji and historical scripts.
What are UTF-8 and UTF-16?
UTF-8 and UTF-16 are Unicode transformation formats that encode Unicode code points into binary. UTF-8 uses variable-length encoding (1-4 bytes), while UTF-16 uses 2 or 4 bytes per character.
Which Unicode encoding is most popular on the web?
UTF-8 is the most popular, used by 98.9% of surveyed websites as of January 2026.
How does the size of text in bytes relate to its length in Unicode?
In UTF-8, the number of bytes per character varies: ASCII characters use 1 byte, but characters from other scripts may use 2-4 bytes, so byte size is not always equal to character count.
What is a control character?
A control character is a non-printable character in a character set that performs a function, such as newline, tab, or carriage return.
What is a code space or code page?
A code space (or code page) is the complete set of code points defined by a character encoding, such as 0-127 for ASCII.
What was the Baudot code?
The Baudot code is an early 5-bit character encoding invented by Émile Baudot in 1870, used in telegraphy, and later standardized as ITA2.
What is EBCDIC?
EBCDIC (Extended Binary-Coded Decimal Interchange Code) is an 8-bit character encoding developed by IBM in 1963 for the System/360, supporting more characters than earlier 6-bit codes.
Why were early character encodings limited?
Early encodings were limited by hardware constraints, often using only 5 or 6 bits, which could represent only a small set of characters like uppercase letters and digits.
What is the difference between ASCII and Unicode?
ASCII is a 7-bit encoding for 128 characters, while Unicode is a comprehensive standard with over a million code points, supporting many scripts and symbols. ASCII is a subset of Unicode.
How many characters can Unicode represent?
Unicode can represent over 1.1 million code points, though not all are assigned yet.
What is a variable-length encoding?
A variable-length encoding uses different numbers of bits or bytes for different characters, like UTF-8 which uses 1-4 bytes per character, to save space for common characters.
What is the purpose of character encoding?
Character encoding allows computers to store, transmit, and process text by mapping each character to a numeric code that can be represented in binary.
What is the ASCII code for the letter 'A'?
The ASCII code for 'A' is 65 in decimal, or 1000001 in binary.
How many bits are in a byte?
A byte consists of 8 bits.
Why is UTF-8 popular on the web?
UTF-8 is backward-compatible with ASCII, uses less space for common Latin characters, and can represent all Unicode characters, making it efficient and widely supported.
What is a character encoding?
A character encoding is a convention that maps each character in a character set to a numeric value (code point) so that text can be stored and processed digitally.
What is the difference between a character set and a character encoding?
A character set is the collection of characters and their code points, while a character encoding is the scheme for representing those code points in binary (e.g., UTF-8).