The MacBook Air M4 is Apple's thin, fanless laptop for people who want a quiet machine that handles everyday work without drama. This review is written as a buying guide rather than a lab report: it summarises the specifications Apple publishes, explains what the M4 chip realistically changes for common workloads, sets honest expectations for battery life and charging, compares the 13-inch and 15-inch models, and walks through the memory and storage decisions that matter most because they cannot be upgraded later. It also names the situations where a different machine — including a cheaper previous-generation Air or a MacBook Pro — is the smarter purchase. Every number quoted below comes from Apple's own published specification sheet, not from tests we ran ourselves.