* **solves [a] problem**: a lifehack must be about solving a concrete problem. It's a “how” question, not a “what” or “why” question.
* **an everyday problem**: a lifehack concerns everyday life. Problems encountered as part of professional life, or requiring specialized knowledge, are not lifehacks.
* **increases productivity or efficiency**: a lifehack is about solving the problem quickly and with few resources, not about finding the solution that produces a high-quality result.