DIGITAL SIGNATURE CERTIFICATE

A Digital Signature Certificate (DSC) is a secure digital key that certifies the identity of the holder, issued by a Certifying Authority (CA). It typically contains your identity (name, email, country, APNIC account name and your public key). Digital Certificates use Public Key Infrastructure meaning data that has been digitally signed or encrypted by a private key can only be decrypted by its corresponding public key. A digital certificate is an electronic "credit card" that establishes your credentials when doing business or other transactions on the Web.

Benefits of a digital signature certificate
Digital Signature Certificates are helpful in authenticating the personal information details of the individual holder when conducting business online.
Reduced cost and time: Instead of signing the hard copy documents physically and scanning them to send them via e-mail, you can digitally sign the PDF files and send them much more quickly. 
The Digital Signature certificate holder does not have to be physically present to conduct or authorize a business
Data integrity: Documents that are signed digitally cannot be altered or edited after signing, which makes the data safe and secure.
The government agencies often ask for these certificates to cross-check and verify the business transaction.
Authenticity of documents: Digitally signed documents give confidence to the receiver to be assured of the signer’s authenticity. They can take action on the basis of such documents without getting worried about the documents being forged.

Classes of DSC
The type of applicant and the purpose for which the Digital Signature Certificate is obtained defines the kind of DSC one must apply for depending on the need. There are three types of Digital Signature certificates issued by the certifying authorities.
Class 1 Certificates: These are issued to individual/private subscribers and are used to confirm that the user’s name and email contact details from the clearly defined subject lie within the database of the certifying authority.
Class 2 Certificates: These are issued to the director/signatory authorities of the companies for the purpose of e-filing with the Registrar of Companies (ROC). Class 2 certificate is mandatory for individuals who have to sign manual documents while filing of returns with the ROC.
Class 3 Certificates: These certificates are used in online participation/bidding in e-auctions and online tenders anywhere in India. The vendors who wish to participate in the online tenders must have a Class 3 digital signature certificate.