  We investigate the potential for observing gravitational waves from
cosmological phase transitions with LISA in light of recent theoretical and
experimental developments. Our analysis is based on current state-of-the-art
simulations of sound waves in the cosmic fluid after the phase transition
completes. We discuss the various sources of gravitational radiation, the
underlying parameters describing the phase transition and a variety of viable
particle physics models in this context, clarifying common misconceptions that
appear in the literature and identifying open questions requiring future study.
We also present a web-based tool, PTPlot, that allows users to obtain
up-to-date detection prospects for a given set of phase transition parameters
at LISA.
