This paper examines what, precisely, is meant by a 'farm' and considers various attributes of farms relevant to an assessment of the structure of European agriculture. A measure of average farm size is proposed to cope with the uncertain count of the population of farms. The issue of tenure may also be complex, with some farms consisting of separate parcels of land, each with different tenure situations. Finally, although many European farmers are often described as being 'part-time', there are a number of different criteria on the basis of which farmers, and also farms, may be classified as being part-time.