What
Testing of an object without execution on a computer.
BS 7925-1.British Computer Society Specialist Interest Group in Software Testing (BCS SIGIST)

Closely related to static analysis, and in practice interchangeable. However static testing is much more focused on actually finding faults.

Static testing is a white box technique. or structural technique. This is because the testing is done with access to the code. The static element means that the program does not have to run, in order to expose faults in the software.

Usually as part of Component Testing

Inspections and reviews are the most important forms of static testing. Inspections or "Fagan" inspections are the most formal technique. Whilst walkthrough reviews are most informal. Any document can be reviewed or inspected.

Why?
The usual suspects apply here, to generate credible info about the state of the software, confidence and identify faults or incidents. An additional consideration is cost. In Boris Beizers well known analysis, the longer a fault stays in the product as it goes through the lifecycle, by a factor of 10 at each stage. This has become a cliche somewhat, but is not without foundation. If the fault can be found by the developer or colleague it will cost tens or hundreds of pounds. If a customer finds the fault, thousands of pounds may be the cost.

Is it proper testing though? Yes, if it finds or prevents faults.

Who?
Ideally by a independent individual or team. The reviewer should understand domain or jargon of the text reviewed. Thus code is reviewed by developers. Requirements gathering documents by analysts. This avoids the risk that, the author will be blind to errors and faults.

Where?
As close as possible to where the docrment was written. There is a balancing act between geographical and organisational proximity versus independence of the reviewing team. Almost certainly at the developing organisations site.

When?
As soon as possible after the document or code is written. However there should be some element of entry criteria into the review process.

How?
Static testing is usually labour intensive, however tools do exist to help the tester. Tools can be used to check the syntax of the code. Thus unclosed instances and unoptimized sql can be highlighted.

In an informal process the developer or analyst may just pass his work across to a colleague. In the Inspection process developed by Fagan there are entry and exit criteria, logging incidents, process improvement and fault resolution and fault eradication.

No matter which process is undertaken, faults or incidents must be recorded either electronically or on paper.