Validation, as performed in pharmaceuticals, is the process of producing documented evidence that a system or process does what it is supposed to do. In a way, it is like QC for engineering.
For equipment, validation typically includes documenting or testing nearly every attribute of the system's construction, in order to demonstrate that it is appropriate for the intended processes. Many organizations refer to equipment validation as "qualification". A complicated system, such as a bioreactor, might have many binders of validation documentation.
For processes, validation involves running the process first at a smaller scale to generate suporting data regarding how closely various parameters need to be controlled. Then, at the full process scale, the process is run with extra testing and documentation to show consistency.
For computer systems (including control systems), the testing and documentation required to show that the system does what is required can be really extensive.
The control required to maintain this validated state tends to make it cumbersome to make changes in processes or systems.
Page updated 11/25/16