This paper looks at the dot com phenomenon drawing mainly on examples from the USA where the boom started and was most pronounced, but also from the UK which had a number of high profile dot coms. It starts by asking the question, ‘Who were the dot coms?’. it then goes on to consider the factors which led to the emergence of the dot coms such as the emergence of the commercial Internet, the lowering of entry barriers which followed from this and the funding available for new businesses through venture capital. The article also looks at the reasons why it was believed that the dot coms represented a threat to established businesses. The article then looks at the booming IPO market for dot coms and the opportunities this provided for exit by venture capital investors. The crash of 2000 is considered, lessons are drawn for entrepreneurs and investors and finally the article will look at future prospects for the dot com sector