# Glossary

**Yield-Bearing Token**

Yield-bearing Token is an umbrella term that refers to any token that generates yield. Examples include stETH, GLP, aDAI or even liquidity provider tokens such as Aura rETH-WETH.

**PT = Principal Token**

PT entitles you to the principal of the underlying yield-bearing token, redeemable after maturity.

If you own 1 PT-stETH with 1 year maturity, you will be able to redeem 1 ETH worth of stETH after 1 year. PT is tradeable anytime, even before maturity.

**YT = Yield Token**

YT entitles you to all the yield generated by the underlying yield-bearing token in real-time.

If you own 1 YT-stETH and stETH has an average yield of 5% through the year, you will have accrued 0.05 stETH by the end of the year.

YT is tradeable anytime, even before maturity.

**Maturity**

When used in conjunction with the Underlying APY, Implied APY can be used to establish the relative valuation of an asset such as YT and PT at their current price, and help traders determine their trading strategies.

The value of Implied Yield is numerically equivalent to the to Fixed Yield APY.

**Fixed APY**

Fixed APY is the guaranteed yield you will receive by holding PT. This value is numerically equivalent to the Implied APY.

**Long Yield APY**

Long Yield APY is the approximated return (annualized) from buying YT at the current price, assuming underlying APY remains constant at its current value.

This value can be negative, meaning that the total value of all the future yield baed on the Underlying APY will be less than the cost of buying YT.

**NPR Token**

Napier govarnance token.

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