The idea
A trust line is your account’s explicit yes to hold an issued token from a named issuer, up to a limit you set. Without that yes, the ledger will not park their token on you.
Group 5 · The trading post
Trust lines
agreeing to hold someone’s token
Why it matters
Holding a token is not the same as holding XRP. You are trusting the issuer’s rules, including freeze or clawback if those flags are on.
How it works
XRP needs no trust line. It is the ledger’s native asset. An issued token is a balance the issuer owes, recorded on a line between your account and theirs. You open the line by setting a limit above zero. The limit is the most of that token you are willing to be paid. You can set the limit back down later, but you cannot set it below what you already hold.
The line also shows the issuer. Two tokens with the same ticker from two issuers are not the same thing. The line names who stands behind it.
Real example: on the XRP Ledger you create a trust line with a TrustSet transaction. Until that line exists, payments of that issued token to you fail. The line is your consent, not a gift of value. Source: Trust Line Tokens.
Picture it
A signed note that you will hold a neighbor’s IOU = trust line. The neighbor’s name is the issuer.
Watch out
A ticker you recognize from a stranger issuer. Read the issuer account, not just the three letters.