Web and Application Servers
Minimum
Windows Server 2008 R2 with Service Pack 1 (Standard, Enterprise, or Datacenter)
Requires KB 2554876, KB 2708075, KB 2759112
Optional
Windows Server 2012 (Standard or Datacenter)
Prerequisites
Database Servers
SQL Server 2008 R2 Service Pack 1
SQL Server 2012
Resources
Learn more about SharePoint Server 2013
Learn more about hardware and software requirements for SharePoint Server 2013
SharePoint Server 2013 System Requirements Training