Definitions of education aim to describe the essential features of education. A great variety of definitions has been proposed. There is wide agreement that education involves, among other things, the transmission of knowledge. But there are deep disagreements about its exact nature and characteristics. Some definitions see education as a process exemplified in events like schooling, teaching, and learning. Others understand it not as a process but as the product of such processes, i.e. as what characterizes educated persons. Various attempts have been made to give precise definitions listing its necessary and sufficient conditions. The failure of such attempts, often in the form of being unable to account for various counter examples, has led many theorists to adopt less precise conceptions based on family resemblance. On this view, different forms of education are similar by having overlapping features but there is no set of features shared by all forms. Clarity about the nature of education is central for various issues, for example, to coherently talk about the subject and to determine how to achieve and measure it.