Background of Staff Selection Commission
The Estimates Committee of the Parliament, in its 47th Report (1967-68), recommended the setting up of a Service Selection Commission for conducting examinations for recruitment to lower categories of posts. Pursuant to this, and as an interim measure, an Examination Wing was initially added to the Secretariat Training School, subsequently renamed as the Institute of Secretariat Training and Management (ISTM).

Setup of the Commission
The Commission is headed by a Chairman who is assisted by two Members and a Secretary-cum-Controller of Examinations. They are further supported by other officers and Staff of the HQ (Organization Chart at Appendix III) and by a Regional Network of offices established at various locations. The Headquarter of the Commission is located at New Delhi.

Functions of SSC
1. To make recruitment to (i) all Group “B” posts in the various Ministries/Departments of the Govt. of India and their Attached and Subordinate Offices which are in the pay scales the maximum of which is Rs.10,500 or below and (ii) all non-technical Group “C” posts in the various Ministries/Departments of the Govt. of India and their Attached and Subordinate Offices, except those posts which are specifically exempt from the purview of the Staff Selection Commission.
2. To conduct examinations and/or interviews, whenever required for recruitment to the posts within its purview. The examinations would be held as far as possible at different centres and successful candidates posted, to the extent possible, to their home State/Region.
3. In particular, to hold Open Competitive Examinations for recruitment to the posts of:
(i) Lower Division Clerks in the various Ministries/Departments, Attached and Subordinate Offices of the Government of India including those participating in the Central Secretariat Clerical Service /Indian Foreign Service (B), Railway Board Secretariat Clerical Service and the Armed Forces Headquarters Clerical Service;
(4). The Commission also holds Departmental Examination for promotion from:
(i) Group “D” to Lower Division Clerk Grade of the Central Secretariat Clerical Service and equivalent grades in Indian Foreign Service (B)/Railway Board Secretariat Clerical Service/Armed Force Hqrs. Clerical Service;
5. The Commission conducts periodical Typewriting Tests in English and Hindi.
6. The Commission prepares schemes for recruitment to all Group “B” posts which are in the pay scale of Rs 9300 to 34800 with a grade pay of Rs 42000 or below and Group “C” non-technical posts in the Ministries/Departmental of the Govt. of India including its Attached and Subordinate Offices in consultation with the Departments concerned.
7. The Commission conducts examinations/selections for recruitment to all Group “B” posts which are in the pay scales the maximum of which is Rs.10, 500 or below and all Group “C” non-technical posts in the Ministries/Departments of the Govt. from time to time.
8. The Commission performs such other functions as may be entrusted to it by the Central Govt. from time to time.

Recruitment to Isolated Posts (Selection)
The selection process adopted by the Commission for recruitment to such isolated posts, known as Selection Posts, includes the folowing elements:-
1) Selection through short-listing of candidates on the basis of percentage of marks obtained in the Essential Qualification followed by interview.
2) Selection through short-listing of candidates on the basis of a screening test followed by interview.
3) Selection through Proficiency Test in the relevent subject/discipline which is essential for the post(s) in question followed by interview.
4) Selection through short-listing on the basis of percentage of marks obtained in the Essential Qualification followed by Skill Test/Interview.

More Details : http://ssc.nic.in/SSC.html