The Race (or “Lizards,” as they're popularly known) are the antagonistic alien species that invades Earth (or Tosev 3, as they call it) during World War II in Harry Turtledove's World War and Colonization series. The Lizards, who have technology slightly in advance of our world's 1990s, are methodical, slow to adapt to changing situations, and are susceptible to getting addicted to ginger, which has drug-like properties to them.
The Race sent a probe to Earth in approximately 1142, observed the planet was primitive, and sent a fleet to invade it after a leisurely preparation period of 1600 Home years (800 Earth years). They assumed that the 'Tosevites' would progress as slowly as the Race and the other races they had previously conquered. This proved to be an incorrect assumption.
The Race, who invade Earth in May 1942, manage to conquer most of the planet, although the major industrialised nations manage to fight them to a standstill, with the United States, Germany, the Soviet Union, Japan, and Britain managing to preserve their independence in 1944. During the course of the conflict, multiple atomic bombs are used by the Lizards and their human enemies.
The Race have become a popular phenomenon on AH.com, particularly in the fields of ASB scenarios and fanfics.
It is thought by many that the Race are partly intended by Turtledove as a critique of the modern military-industrial complex, especially in a Gulf War (1991) context as the first Worldwar book was published soon after that conflict. The Race are at a similar level of technology to the Desert Storm forces there, similarly overrate their air power and technological advantage, and have an exaggerated fear of nuclear weapons compared to the contemporary humans (much like modern people compared to 1940s people).
On the other hand, there is also an 'alien' aspect to the Race, which can be summarised thusly:
Home: Their homeworld. Second planet of Tau Ceti. See above.
Rabotev 1: First planet of Epsilon Eridani. Home to the Rabotev race, who appear similar to the Race but are taller, darker and have eyes on the end of stalks instead of chameleon-like eye turrets as the Race have.
Halless 2: Second planet of Epsilon Indi. Home to the Hallessi race, who are shorter than the Race and have more human-like proportions, but are nonetheless still reptilian.
Tosev 3: Earth - third planet of 'Tosev' (Sol). Home to the 'Tosevite' (human) race, nicknamed Big Uglies by the Race. Earth is towards the cooler end of what the Race consider to be the habitable distance from its primary, and has more water and 'frozen water' (ice) than any other Race planet.
Bannership: i.e. flagship. Turtledove is not known for his imagination.
Fleetlord: Commander of a fleet.
Shiplord: Commander of a ship. All Race ships are named after past emperors, of which there are many (the Empire having lasted for 100,000 Home years, about 50,000 Earth years).
Killercraft: War plane (can be fighter or bomber).
Landcruiser: Tank (a little used OTL term).
-male: The Race use 'male' for 'man' in military contexts, i.e. 'infantrymales', 'wingmales', etc.
Soldiers' Time: A generational period in which a conquest is planned, and soldiers are recruited and trained alongside the other vocations on Home (which are chosen by computer). The Race found it hard to cope with the requirements of maintaining a continuous standing army on Earth, as previously they had simply called up one generation of soldiers, conquered a planet easily, and then that was that for a few thousand years until the next conquest.