Cloud testing is used in different ways, the cause is the word cloud is used for everything. Mostly cloud testing is the testing of cloud computing, the hardware and the availability, but also testing the behaviour of the application when up or down scaling the server capacity for example.
Software Testing as a Service, is a manner for testing software from a client who outsourced his testing activities to a specific testing provider. The testing provider delivers the work in the time and budget they agreed off. The unique selling point is that they use a standard strategy, standard test cases to be a competitor for the current testing companies. Mostly the tests are executed at the location of the testing provider. You can see this a specific kind of near shoring with some specific characteristics. The testers are professional test experts using proven methodologies.
Global outsourcing can have the same characteristics like STaaS; if you are talking about the approach, the risks, results and time needed for the execution. The difference lies in the fact that global outsourcing doesn’t take place in a specific country but worldwide. It´s important to realize that the test take place with a controlled environment, so you have a good insight in the quality of the application.
Crowdtesting is for the current testing companies maybe the most innovative way of testing their work. Crowdtesting is the use of a crowd of people and knowledge when testing software applications or systems. An import difference with traditional testing is that the test is focuses on accepting the software instead of finding defects and has a different reward compared to nowadays.
A crowd consists of people all over the world from different background, cultures and companies. This potential crowd of billions can test for you and your client! So everybody in the world can be part of the crowd; that Eskimo in Alaska or the nomads of the Sahara.