Hello,

If your query is specifically for UPSC Civil Service Exam then you need to be a graduate from a recognized University in order to appear for the exam, or you can also apply in the final year, you need to be at least 21 years old as on 1st August of the appearing year, UPSC CSE is conducted in three stages mainly such as

Prelims which is mcqs based, it has two papers and both are of 200 marks each, to qualify paper I you need to score the required cut-offs against your respective category,
paper II which is qualifying by nature named CSAT where you need to attain merely 33% that is 66 marks out of 200,prelims scores are not added in the final list

The prescribed syllabus for each paper is as follows

Paper I has History of India and Indian national movement, Indian and World geography, Economic and social development- sustainable development, poverty,inclusion demographics, social sector initiatives etc,Indian polity and governance-constitution,political system,Current Events nationally and Internationally, General Science,General Issues on environmental ecology,biodiversity and climate change. you just need to score the required cut offs against your category.

Paper II has basic numeracy, comprehension, logical reasoning and analytical ability, general mental ability, decision making and problem solving, interpersonal skills including communication skills

Next stage is Mains, which is more descriptive by nature, you need to write answers for the same, it includes four GS papers such as

Four General Studies Paper such as

GS-I includes Indian Heritage and Culture,History and Geography of the World and Society,
GS-II includes Governance, Constitution, Polity, Social Justice and International Relations,
GS-III includes Technology, Economic Development, Bio-Diversity, Environment, Security and Disaster Management,
GS-IV includes Ethics, Integrity, and Aptitude

In addition to above there are two optionals, one essay,
two Language Paper, so there are a total of nine paper out of which two language papers are qualifying by nature and each is of 300 marks, you need to score only 25% that is 75 marks to qualify, for the rest of the paper each is of 250 marks,

Last stage is personality test of 275 marks, hence the total marks attributed in UPSC CSE is 2025 marks.