Wat is Linear, inverse and quanto contracts?

A linear contract is quoted and settled in the quote currency (a dollar or a stablecoin), its P&L linear in the price: $q\,(S - E)$ for $q$ units bought at $E$. An inverse contract has a fixed notional in the quote currency but is margined and settled in the underlying coin, so that $N$ contracts of one dollar each bought at $E$ earn $N\,(1/E - 1/S)$ coins. A quanto contract is quoted on one asset but margined and settled in another at a fixed rate per unit of price move, so that its P&L in the settlement asset is $N\,m\,(S - E)$ for a multiplier $m$, whatever the settlement asset’s price.