Bitcoin is a digital decentralized unstoppable form of money that you can buy, sell and exchange directly, without an intermediary like a bank. It uses peer-to-peer technology to operate with no central authority; managing transactions and the issuing of bitcoins is carried out collectively by the network. Bitcoin is open-source; its design is public, nobody owns or controls Bitcoin and everyone can take part. You can learn more on bitcoin.org.
The Lightning Network is a layer built on top of Bitcoin. It allows for faster payments by processing transactions away from the main blockchain - while keeping the same decentralization and security. You can learn more on lightning.network.
In Settle Up you can settle your debts via the Lightning Network. To facilitate that you send the payment to us and we forward the recipient a link where they can in turn withdraw these funds into their own wallet. There is a small fee which we charge the sender, this is displayed transparently before the initial payment is made. The recipient doesn't pay any fees. If the recipient doesn't claim the payment we will issue the sender a dedicated link where they can take the payment back.
There are many Lightning wallets you can choose from. There are 2 categories - custodial and non-custodial.