Before releasing products for sale, companies often pretest their products for safety and reliability. This process typically involves detecting and fixing errors and making improvements if necessary. In the computer industry, pretesting can be performed on both hardware and software.
Computer hardware manufacturers often pretest their products rigorously before distributing them to the public. For example, a hard drive may be tested in extremely hot and cold temperatures to determine what the safe operating temperature of the hard drive is. A chip manufacturer may test a CPU under a maximum processing load for an extended period of time to make sure it does not overheat. Hard drives, CPUs, and RAM are all tested for reliability, since small errors can cause major problems. Modern computers can perform billions of calculations per second, so even one miscalculation per billion is considered highly unreliable.
Software is also pretested before it is made available for sale. The amount of pretesting is generally determined by the size and complexity of the program. Initially, pretesting is done by the software development team, as the initial bugs are worked out. Then the software may go through an "alpha" phase, where the developers and possibly other users test the software. As the program nears completion, it may go through a "beta" phase, where additional users can test the software and provide feedback to the developers. This software is called beta software and may be distributed to a select group of users or the general public. Once the beta stage is complete, the software is ready for sale.