Well-being, or wellbeing, also known as wellness, prudential value, prosperity or quality of life, is what is intrinsically valuable relative to someone. So the well-being of a person is what is ultimately good for this person, what is in the self-interest of this person. Well-being can refer to both positive and negative well-being. In its positive sense, it is sometimes contrasted with ill-being as its opposite. The term "subjective well-being" denotes how people experience and evaluate their lives, usually measured in relation to self-reported well-being obtained through questionnaires.

कल्याण या भलाई किसी व्यक्ति या समूह की वह स्थिति होती है जो किसी अर्थ में "अच्छी" कहलाई जा सके। इसमें कई आयाम सम्मिलित हैं, जैसे कि शारीरिक, मानसिक, सामाजिक, आर्थिक, मनोवैज्ञानिक, आध्यात्मिक या चिकित्सा अवस्था। भलाई की सकारात्मक अवस्था में व्यक्ति या समूह के पास स्वेच्छा से कई प्रकार के विकल्पों में चुनाव कर पाने का अधिकार व क्षमता होती है।