We introduce timed automata and show how they can be used for the specification of timed systems. We also present some syntactical extensions useful for modeling and in particular networks of timed automata. Then we present two techniques for the analysis of timed automata: the zone graph and the region graph. The former can be more efficient for reachability analysis and related problems but it is not always finite. In contrast, the latter is a finite graph and can be used for model-checking. We compare the properties fulfilled by finite automata and timed automata emphasizing their main differences: languages of timed automata are not closed under complementation and the inclusion of languages is undecidable for timed automata.