Dukkha

Buddhism
Basic terms
Three Jewels Four Noble Truths Dukkha Samudaya Nirodha Marga Noble Eightfold Path Buddhahood Enlightenment Nirvana
People
Gautama Buddha Dalai Lama Bodhisattva Sangha
Schools
Theravada Mahayana Zen Vajrayana Nyingma Kagyu Sakya Gelug
Practices
study Dharma Meditation Metta

Dukkha is an important concept in Buddhism. It is usually translated as "suffering". It is about understanding why people are unhappy. It is one of the Four Noble Truths.