Attosecond pulses, generated as either single bursts or a train of pulses, are among the most celebrated offspring of strong field physics. They are also among the most exciting new tools available for studying and controlling strong field phenomena. In this talk we highlight some of the single atom as well as macroscopic strong field physics which is crucial for the generation of single attosecond pulses. We also discuss how attosecond pulse trains can be tailored for specific applications such as non sequential double ionization and the creation of novel attosecond electron wave packets.