Here we present a science background for each of the five themes of the ALMA proposal categories, including some recent results when applicable. The intention with this expose is not to be exhaustive regarding the science that can be done with ALMA, but rather serve as a general guideline and inspiration to what is possible to achieve with the ALMA observatory. The recent results will be updated on a regular basis, so please stay tuned.

1. Cosmology and the high redshift universe
2. Galaxies and galactic nuclei
3. ISM, star formation and astrochemistry
4. Circumstellar disks, exoplanets and the solar system
5. Stellar evolution and the Sun