From Wikipedia

[means action, work or deed; [1] 

it also refers to the spiritual principle of cause and effect where intent and actions of an individual (cause) influence the future of that individual (effect). [2] 

Good intent and good deeds contribute to good karma and happier rebirths, while bad intent and bad deeds contribute to bad karma and bad rebirths.[3][4]

The philosophy of karma is closely associated with the idea of rebirth in many schools of Indian religions (particularly Hinduism, Buddhism, Jainism and Sikhism[5]) as well as Taoism.[6] In these schools, karma in the present affects one's future in the current life, as well as the nature and quality of future lives – one's saṃsāra. [7][8]