The Preliminary Examination for Civil Services is also popularly called CSAT or Civil Services Aptitude Test. The CSAT is actually the second paper of General Studies that was introduced in 2011.

UPSC Civil Services Exam is conducted in three phases:

Phase 1: Preliminary Examination or CSAT (Objective Section)
Phase 2: Main Examination (Subjective Section)
Phase 3: Interview (Vocal Section)

GS Syllabus For UPSC Prelims

The syllabus for the Preliminary Exams for Paper-I:

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
General Science

The syllabus for the Preliminary Exams for Paper-II:

Comprehension
Interpersonal skills including communication skills;
Logical reasoning and analytical ability
Decision-making and problemsolving
General mental ability
Basic numeracy (numbers and their relations, orders of magnitude, etc.) (Class X level), Data interpretation (charts, graphs, tables, data sufficiency etc. - Class X level)

Important dates:

The official notification was out on 22nd February 2017
Final date for submitting the application form 17th March 2017
The Civil Services Exam 2017(Pre) 18th June 2017
Date of main examination 28th October 2017