This chapter embarks on an in-depth exploration of SQL Server Clustering, a critical technology for ensuring high availability and resilience in database environments. In today’s world, where uninterrupted access to data is crucial, clustering stands out as a key solution. This chapter will guide you through the essential aspects of understanding, implementing, and managing SQL Server clusters. We will begin by establishing a fundamental understanding of the architecture of SQL Server clusters, including the underlying concepts of failover clustering. We will then delve into the various components of a SQL Server cluster, exploring how these components work in harmony to provide continuous availability. Further, we will analyze the advantages and benefits that a cluster can provide, as well as the various types of cluster models that are available. We will then examine SQL Server cluster scenarios and look at testing SQL Server 2019 failover clusters. Finally, we will explore failover methodologies. Ultimately, this chapter is designed to equip you with the knowledge to deploy and maintain reliable and robust SQL Server clusters.