This is a tricky question. Strictly speaking, an organ is a structure that comprises at least two kinds of tissue that function together for a common purpose. Taking this definition some people would say we have 78
However, most people tend to consider vital organs or organ systems.
We have 12 organ systems (such as digestive, immune, reproductive, nervous etc) and most people agree we have 5 vital organs: the brain, the heart, the liver, the lungs, the kidneys