The past two decades have seen a renaissance in the study of symbiotic stars, and modern results have established these objects as belonging to an independent class of binary system. The next decade will see a new generation of satellite observatories, and many cherished theories may crumble under the onslaught of information from Space Telescope, the Hopkins Ultraviolet Telescope, the Extreme Ultraviolet Explorer, and the Advanced X-ray Astronomy Facility (among others). However, the basic properties of symbiotic stars are now well-established, and it is important to understand these characteristics when planning future observational and theoretical projects.

1. Symbiotic stars are binaries with periods ranging from ∼200 days to > 10 years. They are members of the old disk population, and therefore have masses of 1-3 M⊙. Spectroscopic orbits are available for a few systems, and these generally confirm kinematic mass estimates.

2. One component of a symbiotic binary is a red giant. In longperiod D-type systems (P>5-10 yr), the giant is a Mira-like variable losing mass in a powerful stellar wind. Most of the giants in the shorter period S-type systems (P<5-10 yr) tend not to exhibit Mira-like behavior, and lose mass at a considerably lower rate. A few short-period systems contain lobefilling giants which transfer material tidally into an accretion disk surrounding a low mass companion.

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