I like the definition that data is about raw facts and observations about things and that information is data that is selected and presented in a way that is comprehendible by the receiver: 'meaningful data'. Meaningful, but not necessarily useful: "Changcheng was founded in 1976 and is one of about 50 domestic Chinese car manufacturers who made 8 million units in 2009". Knowledge is information that is worthwhile remembering: "China makes lots of cars". Where data, information and knowledge are artifacts, I treat understanding and wisdom primarily as verbs. Understanding is the process of taking information and knowledge and figuring out the 'why', resulting in more information and maybe knowledge: "Cars manufacturing is important for China's economic development". Similarly, wisdom is the process of putting a value on information and knowledge: "Good for China".