Dear Shalaka,
Prior to joining a company the Employee verification process will be taken up. The process includes whether the incumbent is involved in any criminal case, whether the documents such as SSC, Degree, Experience Certificate, etc. will get verififed from the concerned authorities. Now a days this process is entrusted to a third party as so many areas are involved. The third party will be paid suitably depending on contract with them. After getting detailed information, the employer will consider appointment of the candidate basing on the findings given by the third party. If it is a small company where the no.of recruitees are less, the HR of the company will make the above process. If it is a big company like INFOSYS OR WIPRO, the third party agency will do the process. Hope I am clear.