Trust on UpTrust is personal, and it works topic by topic. You might trust a neighbor on gardening and not on politics, and UpTrust keeps those separate. This record of who you find trustworthy, and on what, is the quiet engine that shapes your feed and keeps strangers and bots from deciding what you see.
Your trust is your own
The trust you place in someone is separate from the trust they place in you. It can point one way and not the other. A stranger starts at zero trust from you. As you read, reply, and vote, you teach UpTrust who you find trustworthy.
Trust flows through people
Say you trust Alice, and Alice trusts Carol. You'll gain a little trust in Carol too, even if you've never met her. That borrowed trust is weaker than your direct trust in Alice, and it fades the further out it travels. This is how you can find good people through the people you already trust, instead of having to vet every stranger yourself.
Because every score is built from your own network, two people can look at the same post and see different numbers. That's working as intended. Read What the numbers mean to see why.
The short version