Cardano is a multi-layered open-source blockchain platform designed for both financial transactions and distributed computing. The platform has its own cryptocurrency, named ADA, that allows you to use the platform, create and execute Smart Contracts, DApps, among others. Cardano is developed and supported by IOHK and was created by Charles Hoskinson, one of the founders of Ethereum, with the aim of offering an improved alternative. It is considered a third-generation blockchain after Bitcoin and Ethereum.
The Shelley Era encompasses the critical first steps in Cardano's journey to optimize decentralization. During the Byron era, the network was federated, but as the Shelley era progresses, more and more nodes will change to be managed by the Cardano community. Once the network participants run the majority of the nodes, Cardano will be more decentralized and as a result, will enjoy greater security and robustness.
Delegation is the process by which ADA holders delegate the stake associated with their ADA to a stake pool. It allows ADA holders that do not have the skills or desire to run a node to participate in the network and be rewarded in proportion to the amount of stake delegated.