The Civil Services Examination is conducted by UPSC every year.
The examination consists of two stages

1.  the Preliminary Examination.
2. the Main Examination (Written and Interview).

The Civil Services Examination is widely considered to be one of the toughest and most sought after examinations in the world, with only about 500- 1000 candidates selected out of more than 2,00,000 candidates who appear every year for the examination.

1.  Indian Administrative Service.
2.  Indian Foreign Service.
3.  Indian Police Service.
4.  Indian P & T Accounts & Finance Service, Group 'A'.
5.  Indian Audit and Accounts Service, Group 'A'.
6.  Indian Revenue Service (Customs and Central Excise), Group 'A'.
7.  Indian Defence Accounts Service, Group 'A'.
8.  Indian Revenue Service (I.T.), Group 'A'.
9.  Indian Ordnance Factories Service, Group 'A' (Assistant Works Manager, Administration).
10.  Indian Postal Service, Group 'A'.
11.  Indian Civil Accounts Service, Group 'A'.
12.  Indian Railway Traffic Service, Group 'A'.
13.  Indian Railway Accounts Service, Group 'A'.
14.  Indian Railway Personnel Service, Group 'A'.
15.  Post of Assistant Security Commissioner in Railway Protection Force, Group 'A'
16.  Indian Defence Estates Service, Group 'A'.
17.  Indian Information Service (Junior Grade), Group 'A'.
18.  Indian Trade Service, Group 'A' (Gr. III).
19.  Indian Corporate Law Service, Group 'A'.
20.  Armed Forces Headquarters Civil Service, Group 'B' (Section Officer's Grade).
21.  Delhi, Andaman & Nicobar Islands, Lakshadweep, Daman & Diu and Dadra & Nagar Haveli Civil Service, Group 'B'.
22.  Delhi, Andaman & Nicobar Islands, Lakshadweep, Daman & Diu and Dadra & Nagar Haveli Police Service, Group 'B'.

No. IAS and IPS are All India Services, whereas others fall under two categories ? Group A & Group B Central Services

Any service is considered better based on the certain reasons. Among them some are as follows

1.  The diversity of opportunities it can provide to the incumbent.
2.  The scope and breadth of decision making in the service.
3.  Facilities that go with the service as perks.
4.  Chances for interacting with other departments than the parent dept.
5.  Stability of career.

The services are allocated based on the final Rank the candidate had secured, Preferences of services executed by the candidate, Category of the candidate and Vacancy of the Post.

The candidate must hold a degree of any of Universities incorporated by an Act of the Central or State Legislature in India or other educational institutions established by an Act of Parliament or declared to be deemed as a University Under Section-3 of the University Grants Commission Act, 1956, or possess an equivalent qualification.

Yes. For Civil Services Exams, the candidate is eligible since the UPSC has not specified the mode of acquiring the degree.

Candidate possessing only a Diploma is not eligible, however if the candidate had done graduation after Diploma he is eligible.

To appear in the exam the minimum age is 21 years on 1st August, on that year. The upper age limit depends upon the category to which you belong. If you belong to

1.  General Category, the upper age limit is 32 years.
2.  Other Backward Classes, it is 35 years.
3.  SC/ST category, upper age limit is 37 years.

For special categories, the age relaxations (from 32 years) are as follows

1.  Blind, deaf-mute and Orthopaedically handicapped persons : 10 years.
2.  Blind, deaf-mute and Orthopaedically handicapped persons + SC/ST : 15 years.
3.  Blind, deaf-mute and Orthopaedically handicapped persons + OBC : 13 years.
4.  Defence Services Personnel disabled in operations : 3 years.
5.  Defence Services Personnel + SC/ST : 8 years.
6.  Defence Services Personnel + OBC : 6 years.
7.  Ex-Servicemen including Commissioned Officers : 5 years.
8.  Ex-Servicemen including Commissioned officers + SC/ST : 10 years.
9.  Ex-Servicemen including Commissioned officers + OBC : 8 years.

No. Generally, any one below the age of 32 years can attempt 6 times. If you belong to

1.  Other Backward Classes, you get 3 more attempts.
2.  SC/ST category, there is no limit in the number of attempts you can make.

The Civil Services Examination will consist of two successive stages

1.  Civil Services Preliminary Exams.
2.  Civil Services Main Examination.
3.  Personality Test.

1.  Civil Services Preliminary Examination: (Objective type) for the selection of candidates for the Main Examination; and
2.  Civil Services Main Examination (Written and Interview) for the selection of candidates for the various Services and posts Preliminary Screening test is only of qualifying nature and the scored in Preliminary Examination will not be taken for ranking Candidates have to go in accordance to the stages in the exam. In the same cycle of the year of exam, candidate should get qualified in all the stages. If the candidate gets disqualified in any of the stages, the candidate should reappear in the preliminary examination next year.