Q. What is karma?
A. All the activities that we do constitute karma.
The Bhagavad Gita defines three types of karma – vikarma, karma and akarma.
Vikarma is those activities that the scriptures ask not to be done and karma is those activities that scriptures prescribe. In both cases we get the reaction to our sinful or pious activities for which we have to be born in this material world again and again to suffer or enjoy. So in the ultimate sense both activities are bad because they do not help in getting liberated from the cycle of birth and death.
Akarma is those activities that are done only with the purpose of pleasing Krishna or in other words devotional service to Krishna which does not entail any karmic reaction and so helps us attain an eternal life of service to Krishna in bliss.