Explore best practices for implementing efficient application-level caching in this PHP UK Conference talk. Discover techniques like 'biggest smallest reusable item' and automatic write-through caching to enhance performance and scalability. Learn about various caching technologies, including Memcached, APC, and Zend Server Cache. Dive into opcode cache options, caching methodologies, and cache invalidation strategies. Gain insights on configuring and managing Memcached, using APC functions, and implementing read-through cache callbacks. Understand concepts such as check and set operations, asynchronous fetching, and multi-layer caching to optimize your PHP applications.