It serves as a link between the blockchain and data from the outside world. Blockchains are
built to be extremely effective in verifying the integrity of data within the network. They are
not, however, capable of determining whether the data is "true" or not. If you want to
incentivize a friend with A4R to run 5 km every day, the blockchain must be reliably fed step
count data from an external source. That source is known as an oracle, in this case the Movement
Oracle.