The co-signer on a loan is a person who vouches for the signing first party in the event he or she is unable to pay. They put their name on the promissory note just like the original borrower and, in most cases, will will incur the same obligations as the original borrower. If the borrower does not make his or her payments, the co-signer can suffer the credit consequences. Both parties are jointly responsible for fulfilling the obligations under the note. People generally need co-signers when they are unable to obtain approval for credit on their own accord. Co-signers can provide the certainty that lenders desire. A co-signer will usually be a person who has a long, extensive credit history. In most cases, they will have the financial means to cover the loan if the original borrower is unsuccessful in paying it back on time or in full.