Which is a central concept in buddhism?

There a few central concepts in Buddhism also known as the Four noble truths.

The first noble truth revolves around the fact that life is suffering and that during our lives, we will suffer in various ways. This entails not only physical suffering like pain or starvation, but also psychological suffering such as anger, sadness, depression, etc. 

The second noble truth revolves around craving, as supposedly every suffering is caaused by craving. 

The third noble truth revolves around avoiding suffering. It is possible for us to be happy and avoid being unhappy and suffer in our life. 

The fourth noble truth revolves around overcoming suffering. The fourth noble truth mainly talks about how can we diminish suffering.