A practical talk focused on Linux system administration and debugging tools for PHP developers. The speaker covers essential Linux concepts and demonstrates powerful troubleshooting techniques using tools like strace, lsof, and PHP-FPM access logs. The talk emphasizes understanding server-side debugging beyond just PHP code, including sessions, file locking, and I/O monitoring.

A comprehensive talk about Varnish HTTP cache server, covering its core functionality, configuration, and implementation. The speaker explains how Varnish works as a reverse proxy and HTTP accelerator, details its configuration language (VCL), and demonstrates how to handle caching, purging, and edge side includes (ESI). The talk includes practical examples of HTTP header manipulation, cache control, and debugging techniques.