What are the main uses of robots?

An industrial robot is officially defined by ISO as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes.
Modern industrial robots are true marvels of engineering. A robot the size of a person can easily carry a load over one hundred pounds and move it very quickly with a repeatability of +/-0.006 inches. Furthermore these robots can do that 24 hours a day for years on end with no failures whatsoever. Though they are reprogrammable, in many applications (particularly those in the auto industry) they are programmed once and then repeat that exact same task for years. Perhaps the most popular applications of robots is in industrial welding. The repeatability, uniformity quality, and speed of robotic welding is unmatched. The two basic types of welding are spot welding and arc welding, although laser welding is done. Some environmental requirements should be considered for a successful operation. The automotive industry is a major user of robotic spot welders. In 1985 Chrysler Motor Corporation's plants had a robot population of 900, 670 of which were used for spot welding.
Another popular and efficient use for robots is in the field of spray painting. The consistency and repeatability of a robot's motion have enabled near perfect quality while at the same time wasting no paint.
Palletizing is the act of loading or unloading material onto pallets. The newspaper industry has been particularly hard hit by increased labor costs. Part of the solution to this problem was to use robots like Cincinnati Milacron Robot being used to palletize advertising inserts for a newspaper.
Many companies in the United States and Canada have been forced to close in such areas as die casting and injection molding because they could not compete with foreign firms. The introduction of robotics into this process has allowed the same companies to remain viable.
Farmers drive over a billion slooooww tractor miles every year on the same ground. Their land is generally gentle, and proven robot navigation techniques can be applied to this environment. A robot agricultural harvester named Demeter is a model for commercializing mobile robotics technology. The Demeter harvester contains controllers, positioners, safeguards, and task software specialized to the needs commercial agriculture.
Dante II's mission was to rappel and walk autonomously over rough terrain in a harsh environment; receive instructions from remote operators; demonstrate sophisticated communications and control software; and determine how much carbon dioxide, hydrogen sulfide, and sulfur dioxide exist in the steamy gas emanating from fumaroles in the crater. Via satellite, Dante II sent back visual information and other data, as well as received instruction from human operators at control stations in Anchorage, Washington D.C., and the NASA Ames Research Center near San Francisco. Dante II saves volcanologists from having to enter the craters of active volcanoes. It also demonstrates the technology necessary for a robot to explore the surface of the moon or planets. That is, the robot must be able to walk on rough terrain in a harsh environment, receive instructions from remote operators about where to go next, and reach those commanded goals autonomously.
The most common type of existing robotic device is the robot arm often used in industry and manufacturing. The mechanical arm recreates many of the movements of the human arm, having not only side-to-side and up-and-down motion, but also a full 360-degree circular motion at the wrist, which humans do not have. Robot arms are of two types. One is computer-operated and programmed for a specific function. The other requires a human to actually control the strength and movement of the arm to perform the task.