Data

Binary addition follows the same rules as normal addition, but only uses the digits 0 and 1.

Binary is a number system that uses only 0s and 1s. It is the language of computers because electronic circuits naturally represent two states: off and on.

A bit is the smallest unit of data in computing, and 8 bits make one byte.

Hexadecimal is a base-16 number system that computer scientists use as a shorthand for binary.

Compression reduces the size of files by encoding the data more efficiently. There are two main types: lossless compression, which preserves every bit of data, and lossy compression, which permanently removes some data to achieve smaller sizes.

Lossless compression reduces file size without losing any data, allowing the original file to be perfectly reconstructed.

Lossy compression reduces file size by permanently removing some data, achieving much smaller files at the cost of some quality.

Run-Length Encoding (RLE) is a simple lossless compression method that replaces consecutive repeated values with a count and a single value.

ASCII is a standard that assigns a unique number to each character so computers can store and share text.

All data in a computer is stored as binary, but different types of data — text, images, and sound — are encoded in very different ways.

Digital images are made up of tiny squares called pixels, each storing colour data as binary numbers.

The Caesar cipher is one of the oldest encryption methods, shifting each letter in a message by a fixed number of positions in the alphabet.

Encryption transforms readable data into an unreadable form so that only authorised parties can access it. It is the foundation of secure communication on the internet.

HTTPS uses encryption to protect data travelling between your browser and a website, keeping your passwords and personal information safe.

Symmetric encryption uses the same key to both encrypt and decrypt data, making it fast but requiring the key to be shared securely.

A file type (or file format) defines how data is organised and stored in a file. Different types are designed for different kinds of content, such as text, images, audio, and data tables.

Different image file formats use different methods to store pixel data, balancing quality, file size, and transparency support.

A text file stores data as plain characters using a character encoding like ASCII or UTF-8.

Study of how data is stored, represented, and processed in computers, including binary, compression, and encryption.