A 64-bit unsigned integer is a data type used in computing that can represent whole numbers without any negative values. It consists of 64 bits, allowing it to store a wide range of values from 0 to 18,446,744,073,709,551,615. This large range makes it useful for applications that require precise and extensive numerical representation, such as in databases or cryptography. Unlike signed integers, which can represent both positive and negative numbers, unsigned integers only account for non-negative values. This characteristic enables 64-bit unsigned integers to maximize the positive range, making them ideal for counting, indexing, and other scenarios where negative values are not needed.