A term sheet summarizes the major economic and control terms of a proposed financing: pre-money valuation, investment amount, share class, liquidation preference, board composition, protective provisions, anti-dilution, and pro rata rights. With a few exceptions (confidentiality, exclusivity), term sheets are non-binding.
Most financings settle most disputes at the term sheet stage. Once the term sheet is signed, definitive documents (Stock Purchase Agreement, Investor Rights Agreement, Voting Agreement) are drafted to implement the terms.