DReps, short for Decentralized Representatives, are key players in Cardano's governance. They are responsible for participating in the voting process and decision-making regarding proposed changes to the Cardano protocol. They can be individuals or entities that hold a certain amount of ADA and have registered as DReps. DReps play a crucial role in ensuring the active participation and inclusivity of the governance process on Cardano.
You can find a DRep list here.
Each DRep votes with all the ADA delegated to them when deciding on the proposals up for a vote. The ADA can be migrated from DRep to DRep at any point.
Similar to the ADA delegated to stake pools, the ADA delegated to a DRep doesn't change ownership; it remains under the control of the original individual(i.e. the user).
Read this guide if you want to become a DRep. Please note that it's currently not possible to cast your votes directly in Yoroi.