The Preliminary Examination of Union Public Service Commission for Civil Services Examination is popularly called CSAT or Civil Services Aptitude Test. The CSAT is actually the second paper of prelimnary General Studies of UPSC IAS syllabus introduced in 2011. The CSAT was introduced to end the use of scaling system for varying subjects in the General Studies paper of UPSC IAS mains examination or whole as IAS syllabus.
The benefit of introducing aptitude tests in the IAS syllabus is that it assesses your logical reasoning and thinking performance. It is based on multiple choice questions answered in exam conditions. No subject influences, or can have an effect on an aptitude test.
Some changes are made in the format of IAS syllabus since 2013. It's for the first time the Indian Forest Service (IFS) aspirants were combined with the Civil Services aspirants and are made to take the preliminary examination. Those Indian Forest Service aspirants who may eventually clear the first stage of exam, they have to write separate exam in place of ias mains examination for their Mains Indian Forest Service examination.
There are several other changes in the pattern of IAS Mains examination from 2013. Now there are four compulsory papers of General Studies of IAS mains examination and only one optional subject instead of two, one compulsory essay paper is also there. Besides, English and one language paper is of only qualifying nature.
Giving an all round approch to the IAS syllabus is the key to success for both preliminary and mains examination.
The UPSC Preliminary Examination shall comprise two compulsory papers of 200 marks each.
• Current events of national and international importance.
• History of India and Indian National Movement.
• Indian and World Geography - Physical, Social, Economic Geography of India and the World.
• Indian Polity and Governance - Constitution, Political System, Panchayati Raj, Public Policy, Rights Issues, etc.
• Economic and Social Development Sustainable Development, Poverty, Inclusion, Demographics, Social Sector initiatives, etc.
• General issues on Environmental Ecology, Bio-diversity and Climate Change - that do not require subject specialization.
• General Science.