Trustlines are a concept unique to Stellar assets. They determine how much of a user-issued asset an account is willing to hold. Since assets on the Stellar network are supposed to be digital representations of fiat currency or other real-world assets, it is essential that the issuer issuing assets should be liquid.

Due to this, you should only hold 100 USD worth of assets that are issued by an issuer account if you know that they can exchange the Stellar USD tokens for 100 dollar bills. Trustlines are indicative of how many liquid assets you believe the asset issuer has and in turn is used to determine how much of the asset you would want your account to hold.

Now, we'll write a Node.js utility so that we can create new assets and extend trustlines to the receiving accounts.