Definition
ACID principles are a set of four essential properties that guarantee reliable processing of database transactions. Atomicity ensures that a transaction is treated as a single, indivisible unit of work, meaning it either completes entirely or fails completely. Consistency guarantees that a transaction brings the database from one valid state to another, preserving data integrity rules. Isolation ensures that concurrent transactions do not interfere with each other, making it appear as if they are executed sequentially. Durability ensures that once a transaction is committed, it is permanent and will survive system failures. These principles are critical for maintaining data integrity and preventing corruption in systems that handle sensitive information, such as financial transaction systems where every deposit or withdrawal must be accurately recorded. A common confusion arises with eventual consistency models, which prioritize availability and performance over immediate transactional integrity. Understanding ACID is fundamental for database administrators and developers, and it frequently appears in IT certifications covering database management and system design.