A4 paper is a standard paper size commonly used for printing and writing. It measures 210 millimeters in width and 297 millimeters in height, which is approximately 8.27 inches by 11.69 inches. A4 paper is part of the ISO 216 standard, which is widely adopted in most countries around the world, except for the United States and a few others that use different paper sizes. This paper size is popular for various applications, including office documents, letters, and reports. A4 paper is typically available in different weights and finishes, making it suitable for both everyday use and professional printing. It is often used in printers and copiers, ensuring compatibility in many settings.