Droids are robotic machines, as found in Star Wars films, books and television series. Mostly created for Star Wars by Special Effects worker John Stears, the term is a clipped form of android. The word droid is a registered trademark of Lucasfilm Ltd. Droids (sometimes also 'droids, short for androids), were robots: mechanical beings, often possessing artificial intelligence. They were used in a variety of roles and environments, often those considered too menial or too dangerous for humans and other species. Droids were also used in fields that required extensive specialization and knowledge, such as medical droids and astromech droids.
Depending on the model and its corresponding purpose, droids were totally obedient, rugged, expendable, capable of vast memory recall, and mathematically precise. These characteristics made them well suited for many jobs, though the lack of independent thought in the cheaper, less advanced models limited their capability. This lack of autonomy was simultaneously a vast asset and a glaring weakness—an asset in terms of obedience and control but a massive drawback in terms of effectiveness. Designers faced a fundamental paradox—make the droids overly intelligent, and they might rebel; yet make the droids not intelligent enough and they would be ineffectual.
Astromech droids 
In Star Wars, Astromech droids (or commonly, Astro droids), were a type of droid that served as automated mechanics, performing a variety of repair duties and often serving as adjuncts or substitutes for nav computers on smaller starships. They were also able to use the mainframe of a larger ship to their advantage. Many starfighters relied on astromech co-pilots.
R2-D2 is an example of an astromech droid.
Trademark use 
The term "Droid" has been used by Verizon Wireless under licence from Lucasfilm, for their line of smartphones based on the Android operating system. Motorola's late-2009 Google Android-based cell phone is called the Droid. This line of phone has been expanded to include other Android-based phones released under Verizon, including the HTC Droid Eris, the HTC Droid Incredible, Motorola Droid X, Motorola Droid 2, and Motorola Droid Pro. The term was also used for the Lucasfilm projects EditDroid, a non-linear editing system, and SoundDroid, an early digital audio workstation.
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