This document summarizes the key components of a SharePoint 2013 farm architecture including:
1. A load balancer distributing requests across web and application servers which have SQL Server configured for high availability through clustering, mirroring or AlwaysOn.
2. Service applications like Search, User Profiles, BCS hosted on application servers.
3. Content databases storing site collections, profiles and service application data.
4. Office Web Apps and Workflow Manager providing additional capabilities.
5. High availability, disaster recovery and physical infrastructure considerations.