Computer software (operating systems, web browsers, word processors, etc.) structure our daily lives. Comprising both a user interface and the electronic circuits of the machine it is printed to, software represents a hybrid object at the crossroads of materiality and immateriality. But is it, strictly speaking, a 'technical object'' By examining the status of software against the criteria of philosophy of classic techniques, in particular that of Gilbert Simondon, this book lays the groundwork of a philosophical reflection on this subject. Further, in order to help introduce readers to problematics, lines of code and explanatory schemas have been provided.