ESI registration is mandatory for establishments with 10 or more employees (in some states, it is 20 or more employees) where the wage limit of employees is up to Rs. 21,000 per month. Once registered, the employer needs to contribute a percentage of the employee's salary to the ESI fund, and the employees also make a nominal contribution.

The benefits provided under the ESI scheme include medical care, sickness benefits, maternity benefits, disablement benefits, dependent benefits, and funeral expenses. It aims to provide financial and medical assistance to employees and their dependents during times of need, such as illness, injury, maternity, or death.

The process of ESI registration involves submitting an application along with required documents such as proof of incorporation, establishment's address proof, PAN card, list of employees, etc., to the concerned regional office of the ESIC. Once the application is processed and approved, the employer is issued an ESI registration number, and they are required to comply with the rules and regulations outlined by the ESIC, including timely payment of contributions and filing of returns.