This simple project use you address from wallet that you connect to it and read is there any ENS DOmains attached to that address.
It only reads domains that you are Registrant not that you are Controller.
For connecting to crypto wallet we use this library RainbowKit.
For quering user domains we use this library Apollo Client to fetch some API data via GraphQL query.
API that we use is the GraphQL API. Here you can find playground to test your GraphQL query: (https://thegraph.com/hosted-service/subgraph/ensdomains/ens)