This document discusses two high availability solutions for MySQL databases: InnoDB Cluster and NDB Cluster. InnoDB Cluster provides built-in high availability features for MySQL 5.7+ that allow for easy setup of highly available and scalable database clusters with features like group replication, MySQL Router for application failover, and management via MySQL Shell. NDB Cluster is an in-memory database that provides high availability through automatic sharding, native APIs, and strong consistency across nodes in the cluster. The document compares the two solutions and outlines the components and goals of InnoDB Cluster.