Validators are nodes that vote in “consensus”: approving and maintaining a record of transactions.
A node must first register with the network to become a validator. This allows token holders to stake (“delegate”) tokens to it and lets the network know that the node wishes to be considered for inclusion in the validator set. Registered nodes will be visible on both the Radix Explorer website and the Desktop Wallet.
Token holders can make their own choice about which validator they wish to delegate staked tokens to, allowing the XRD token holding community to effectively vote on the best validators (and receive incentive rewards when those validators do the right thing). Delegating stake is an important aspect of network security, and you should choose which validators to stake to wisely.
At the beginning of each epoch, the Radix Protocol will automatically select the 100 validator nodes with the most delegated stake to become the validator set. This stake is the sum of both self-stake and delegated stake. The validator set then participates in consensus until the end of that epoch, and the cycle repeats.
Radix will therefore be fully decentralized and permissionless from the start.
For the fully sharded Radix Xi’an release, there will be no limit to how many validators can participate.