Meaning & Definition
ASCII (American Standard Code for Information Interchange)
ASCII stands for “American Standard Code for Information Interchange.” It is a character encoding standard used for representing text and control characters in computers and communication equipment, particularly in the United States and other English-speaking countries. ASCII assigns a unique numerical value to each character, which allows computers to store, process, and exchange text-based information.
Here are some key features of ASCII:
- Character Representation
ASCII represents a wide range of characters, including letters, numbers, punctuation marks, control characters, and various special symbols. Each character is assigned a unique 7-bit binary code, providing a total of 128 possible characters.
- Control Characters
In addition to printable characters, ASCII includes control characters that have specific functions, such as line feed, carriage return, and tab. These control characters are used to control text layout and communication.
- Basic Set
The first 32 ASCII characters (from 0 to 31) are control characters used for formatting and control purposes. For example, character 10 represents a line feed, character 13 represents a carriage return, and character 9 represents a tab.
- Printable Characters
The next 95 characters (from 32 to 126) represent printable characters, including letters, numbers, punctuation, and some special symbols. These characters are the ones typically seen in text documents.
- Extended ASCII
While the original ASCII standard used 7 bits, various extended versions of ASCII were developed to accommodate additional characters and symbols. One well-known example is the ISO 8859-1 standard, which extends ASCII to 8 bits, adding characters for Western European languages.
As computer systems and networks became more global, the limitations of ASCII and extended ASCII became evident. The Unicode standard was developed to encompass characters from various writing systems worldwide. UTF-8, a variable-width character encoding based on Unicode, is now widely used to support international character sets while retaining compatibility with ASCII.
- Binary and Decimal
ASCII characters are represented both in binary (using 7 bits) and in decimal (using decimal values from 0 to 127). For example, the letter “A” is represented as 01000001 in binary or 65 in decimal.
ASCII encoding is fundamental to computer communication and data storage. While it’s less commonly used for character encoding in modern applications (due to the adoption of Unicode), it is still important for legacy systems and low-level computer operations.
ASCII has played a critical role in the history of computing and remains a foundational standard for text representation in many computer systems and programming languages. It was the basis for many early computer terminals, and it continues to be an essential component of various data transmission protocols, including email, FTP, and HTTP.