Hollerith cards, also known as punched cards or IBM cards, are a type of data storage medium that were widely used in the early 20th century for computerized data processing. Invented by Herman Hollerith in the late 19th century, Hollerith cards revolutionized the way data was collected and processed.
Hollerith cards are rectangular pieces of stiff paper or cardboard, measuring around 3.25 by 7.375 inches (8.3 by 18.7 cm). They contain a series of holes, which are punched according to a specific code to represent data. Each column on the card can hold a single character or piece of information, such as a number, letter, or symbol.
These cards were primarily used with electromechanical tabulating machines, designed to read and process the data encoded on the cards. By inserting the cards into the tabulating machine, data could be retrieved and manipulated, allowing for tasks such as census tabulations, payroll calculations, and inventory management.
The punched holes on Hollerith cards were clustered in specific positions, representing different information fields, making it possible to sort, count, and extract data quickly and accurately. This made them particularly invaluable for large-scale data processing, where physical storage space was limited.
Although Hollerith cards eventually became obsolete with the advent of electronic storage systems and computer memory, they played a fundamental role in the early development of data processing and computer technology.
