Step 1: Define.
Also called \emph{partnership agreement}; while writing is not compulsory, a deed avoids disputes and overrides default rules of the Partnership Act.
Step 2: Contents (indicative).
Names/addresses, business nature, capitals, profit/loss ratio, interest on capital/drawings, partners’ remuneration, admission/retirement clauses, valuation of goodwill, settlement on dissolution, arbitration, etc.
Final Answer:
\[
\boxed{\text{Written agreement defining partners’ rights, duties & PSL ratio}}
\]
% Quciktip