A4

A4 refers to a standard paper size commonly used for printing and documents, measuring 210 millimeters by 297 millimeters (8.27 by 11.69 inches). It is part of the ISO 216 international paper size system, which is used in most countries outside North America. The "A" series sizes are based on a consistent aspect ratio, making it easy to scale documents up or down while maintaining proportions. A4 paper is widely used for letters, reports, and other printed materials due to its practical size for everyday use.