SST is short for Social Studies, often called Social Science. It is the school subject that brings together history, geography, civics (political science) and economics under one head. In most Indian schools SST is taught from the upper-primary grades through secondary, and at the board level it is examined as Social Science.
In Indian schools
For a school office, SST is simply one of the core subjects a class is timetabled and staffed for. The teaching and the marks live with the teacher; what the administration tracks is the student, the batch and the attendance behind the subject.