Dukkha

The Four Noble Truths are at the basis of Buddhist belief.
All four truths have to do with suffering; dukkha

Truth 1 simply states that there is suffering

The dukkha of ordinary suffering (dukkha-dukkha) - the obvious physical and mental suffering associated with birth, growing old, illness and dying.

The dukkha produced by change (vipariṇāma-dukkha) - the anxiety or stress of trying to hold onto things that are constantly changing.

The dukkha of conditioned states (saṃkhāra-dukkha) - a basic unsatisfactoriness pervading all forms of existence, due to the fact that all forms of life are changing, impermanent and without any inner core or substance. On this level, the term indicates a lack of satisfaction, a sense that things never measure up to our expectations or standards.

Truth 2 states that craving is the cause of suffering

Craving for sense-pleasures (kama-tanha): this is craving for sense objects which provide pleasant feeling, or craving for sensory pleasures.

Craving to be (bhava-tanha): this is craving to be something, to unite with an experience. This includes craving to be solid and ongoing, to be a being that has a past and a future,  and craving to prevail and dominate over others.

Craving not to be (vibhava-tanha): this is craving to not experience the world, and to be nothing; a wish to be separated from painful feelings.

Truth 3 states that suffering can be ended

Craving for sense-pleasures (kama-tanha): this is craving for sense objects which provide pleasant feeling, or craving for sensory pleasures.

Craving to be (bhava-tanha): this is craving to be something, to unite with an experience. This includes craving to be solid and ongoing, to be a being that has a past and a future,  and craving to prevail and dominate over others.

Craving not to be (vibhava-tanha): this is craving to not experience the world, and to be nothing; a wish to be separated from painful feelings.

Truth 4 states that there is a way (path) out of suffering: the Eight Fold Path

The fourth noble truth is the path to the cessation of dukkha. This path is called the Noble Eightfold Path, and it is considered to be the essence of Buddhist practice. The eightfold path consists of: Right Understanding, Right Thought, Right Speech, Right Action, Right Livelihood, Right Effort, Right Mindfulness, and Right Concentration.
While the first three truths are primarily concerned with understanding the nature of dukkha (suffering, anxiety, stress) and its causes, the fourth truth presents a practical method for overcoming dukkha. The path consists of a set of eight interconnected factors or conditions, that when developed together, lead to the cessation of dukkha. Ajahn Sucitto describes the path as "a mandala of interconnected factors that support and moderate each other."
Thus, the eight items of the path are not to be understood as stages, in which each stage is completed before moving on to the next. Rather, they are to be understood as eight significant dimensions of one's behaviour—mental, spoken, and bodily—that operate in dependence on one another; taken together, they define a complete path, or way of living.