A hobby is considered to be a regular activity that is done for enjoyment, typically during one's leisure time. Hobbies include collecting themed items and objects, engaging in creative and artistic pursuits, playing sports, or pursuing other amusements. Participation in hobbies encourages acquiring substantial skills and knowledge in that area. A list of hobbies changes with renewed interests and developing fashions, making it diverse and lengthy. Hobbies tend to follow trends in society. For example, stamp collecting was popular during the nineteenth and twentieth centuries as postal systems were the main means of communication; as of 2023, video games became more popular following technological advances. The advancing production and technology of the nineteenth century provided workers with more leisure time to engage in hobbies. Because of this, the efforts of people investing in hobbies has increased with time.

Leisure has often been defined as a quality of experience or as free time. Free time is time spent away from business, work, job hunting, domestic chores, and education, as well as necessary activities such as eating and sleeping. Leisure as an experience usually emphasizes dimensions of perceived freedom and choice. It is done for "its own sake", for the quality of experience and involvement. Other classic definitions include Thorstein Veblen's (1899) of "nonproductive consumption of time." Free time is not easy to define due to the multiplicity of approaches used to determine its essence. Different disciplines have definitions reflecting their common issues: for example, sociology on social forces and contexts and psychology as mental and emotional states and conditions. From a research perspective, these approaches have an advantage of being quantifiable and comparable over time and place.