In positive psychology, flow, also known as zone, is the mental state of operation in which a person performing an activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity. In essence, flow is characterized by complete absorption in what one does. Named by Mihály Csíkszentmihályi, the concept has been widely referenced across a variety of fields, though has existed for thousands of years under other guises, notably in some eastern religions.[2] Achieving flow is often referred to as being in the zone.

According to Csikszentmihalyi, flow is completely focused motivation. It is a single-minded immersion and represents perhaps the ultimate experience in harnessing the emotions in the service of performing and learning. In flow, the emotions are not just contained and channeled, but positive, energized, and aligned with the task at hand. The hallmark of flow is a feeling of spontaneous joy, even rapture, while performing a task[3] although flow is also described (below) as a deep focus on nothing but the activity – not even oneself or one's emotions.

Flow has many of the same characteristics as (the positive aspects of) hyperfocus. However, hyperfocus is not always described in a positive light. Some examples include spending "too much" time playing video games or getting side-tracked and pleasurably absorbed by one aspect of an assignment or task to the detriment of the overall assignment. In some cases, hyperfocus can "capture" a person, perhaps causing him or her to appear unfocused or to start several projects, but complete few.