The Permanent Account Number (PAN) is a 10-digit number issued by the Income Tax Department to track monetary transactions and prevent tax evasion. It is unique, national, and permanent. Quoting PAN is mandatory on tax returns and correspondence with tax authorities, as well as on tax payment challans from January 2005. When applying for a PAN card, applicants must use the correct form, provide identification documents, fill out all details accurately, and follow other dos and don'ts outlined in the document.