It is mandatory for all income tax taxpayers or persons who have to file income returns (even on behalf of others), to have a Permanent Account Number (PAN). Your Permanent Account Number (PAN) is a 10-digit alphanumeric identifier, issued by the Income Tax Department. Each taxpayer (e.g. individual, firm, company, etc.) is issued a unique PAN Number, and it is compulsory to quote your PAN Number on return of income tax.
While making an application for a PAN Number, it is mandatory to quote your Aadhaar/Aadhaar Enrolment ID. You can get an instant PAN by providing your Aadhaar details. Once you have applied for a PAN, you can also check the status of your PAN application. If there are any changes in your PAN/Aadhaar details, you can update the details.
Read more here about the procedure for obtaining a PAN number.