A bitmask is a sequence of bits that can be used to manipulate or query specific bits within a binary number. It allows programmers to perform operations like setting, clearing, or toggling bits efficiently. By using bitwise operations, such as AND, OR, and XOR, a bitmask can help manage multiple boolean flags within a single integer. For example, if you have a set of options represented by bits, a bitmask can help you check which options are enabled. This technique is commonly used in programming languages like C, C++, and Python for tasks such as managing permissions or feature toggles in software applications.