A byte stream is a sequence of bytes that can be read from or written to a data source, such as a file or network connection. It allows for the transfer of binary data, making it suitable for various applications, including file handling and communication between devices. Byte streams are essential in programming languages like Java and Python, where they facilitate input and output operations. In a byte stream, data is processed one byte at a time, which can be efficient for handling large amounts of data. This contrasts with character streams, which deal with text data. Byte streams are commonly used in scenarios where precise control over data representation is required, such as in multimedia files or network protocols.