Digital data

Digital data is information represented as a string of discrete symbols. Each symbol in the string comes from a finite alphabet, such as letters or digits. In modern information systems, the most common form is binary data. Binary data uses a string of binary digits, also known as bits. Each bit can only have one of two values: 0 or 1.

This differs from analog data. Analog data uses a continuous range of real numbers. For example, the air pressure variation in a sound wave is analog. Digital data is much more specific and easier for machines to process.

Converting symbols into digital data involves specific technical processes. For simple symbols like alphanumeric characters, computers use polling and encoding. In a polling system, a group of switches is checked at regular intervals. The device checks which switches are currently active. If two switches are pressed within one interval, data may be lost. A specialized processor often handles this polling to avoid burdening the main CPU. Once a symbol is entered, the device sends an interrupt to the CPU. This signal allows the CPU to read the new information.

Complex devices like computer keyboards use a more advanced method called a scan matrix. This is a grid where switches sit at the intersections of x and y lines. To find which keys are pressed, the system performs scanning. It activates each x line one by one in a sequence. It then detects which y lines receive a signal. When a change is detected, the keyboard processor sends a scan code to the CPU. The symbol is then encoded into a number. This process depends on the status of modifier keys, like shift or control.

The term "digital" has deep historical roots. It comes from the Latin word "digitus," which means finger. This connection exists because fingers are frequently used for counting. In 1942, mathematician George Stibitz applied the word to a new field. He used "digital" to describe fast electric pulses in a device used to aim anti-aircraft guns. Today, the term is most common in computing and electronics. It is used whenever real-world information, like audio or photography, is converted into binary numeric form.

The shift toward digital technology has been incredibly rapid. In 1986, less than 1% of the world's technological storage capacity was digital. By 2007, this figure had grown to 94%. A major milestone occurred in 2002. This was the year humankind began storing more information in digital formats than in analog formats. This moment is often called the beginning of the digital age.

This transition changed how almost all global information is managed.

Digital data exists in three distinct states: at rest, in use, and in transit. Data at rest is information housed physically on storage media. This includes hard drives, USB drives, archives, and cloud storage. Data at rest can be structured or unstructured. Because it sits in storage, it is a target for hackers. Organizations use data-at-rest protection (DARP) to secure it. This includes methods like password protection and data encryption. Some systems even use tokenization, which replaces sensitive data with non-sensitive substitutes called tokens.

Data in use refers to active data being processed. This data is stored in a non-persistent or volatile state. Common examples include computer random-access memory (RAM), CPU caches, and CPU registers. Because data in use is active, it is highly sensitive. It can contain encryption keys or intellectual property. If someone accesses the RAM, they might find the keys needed to unlock data at rest. Protecting this state is a major concern for businesses and government agencies.