Nodes of a distributed system need to coordinate to make common decisions and solve a common problem. A leader of a group of processes in a distributed system manages various group activities such as making decisions and routing of messages. A main coordination problem is the election of a leader when the leader stops functioning. Synchronizers are middleware procedures that provide synchronous operation of algorithms in an asynchronous environment. In this chapter, we review leader election algorithms; implement them in Python using mpi4py and describe synchronizers.