Cluster

MS SQL supports clustering.

First of all it supports Failover Cluster Instances. That is applicable to single SQL server instance across multiple Windows Server Failover Clustering ( WSFC ) nodes. In case if one of the nodes crashes, SQL server automatically passes execution to another one.

Second option is Always On Availability Groups. In this case, each availability group consists of primary replica and one or more secondary replicas. In case of crash, secondary replica becomes primary one. 

If to compare WSFC vs Always on, then Always on doesn't require shared storage.