What are tradelines?
A tradeline is basically any account appearing on your credit report. A tradeline keeps a record of creditor’s information to calculate his credit report. You can mutually benefit from someone with positive credit history and improve your credit score if he adds you as an authorized user (AU).Most people ask their family and friends to add them as their AU, but if you want a quick improvement to your credit score, you can add users with exceptional credit history as an authorized user. These AU provide positive data regarding:
(Payment History, Amount owed, Length of history)

Fair Isaac Corporation (FICO) places a credit score in 5 different grades.
720-850 Excellent
660-719 Good
620-659 Average
580-619 Below Average
350-579 PoorBuying
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2-3 seasoned tradeline can help you jump to a 720-850 credit score in a month.