The goal of this research project is to analyze the transactions occuring in Bitcoin and other major cryptocurrencies in order to characterize them. Because Cryptocurrencies use distributed, open ledgers stored in a blockchain, the history of all transactions between (anonymous) addresses can be harvested. Our objective is to use techniques from Machine Learning, Data Mining and Network Analysis to discover meaningful information about those originally anonymous transactions. Our main objective is to estimate types of usages of a particular currency, and the evolution of these usages.