As a suffix to a module it stands for Integration Service. Anything consuming external databases and systems usually gets this suffix.

Clarify your question if that is not what you were searching for..

Hi Ak.

A small search and you would have find the following documentation:

https://www.outsystems.com/evaluation-guide/rest-apis-and-soap-web-services/

Regards,

Daniel

Hi Ak,

Adding to the above answers, Here you can learn the real time use case of API's. That would be great if you go through this one,

https://www.outsystems.com/training/courses/116/integrating-with-web-services/

Thanks,

Ajit Kurane.