what is the eightfold path (Buddhism)?

The Eightfold Path comes from the Fourth Noble Truth, which states that there is a path to end suffering. Check out the Four Noble Truths here.

The path is a way of being, acting, and thinking in the world; it is akin to a moral compass guiding us through life in order to end our suffering. It is practiced in order to understand the true nature of reality and rid ourselves of greed, hatred, attatchment, and the like (which is the root cause of our suffering according to the Buddha).

The Eightfold Path:

Right View (Understanding)
Right Intention (Thought)
Right Speech
Right Action
Right Livelihood
Right Effort
Right Mindfulness
Right Concentration