Siddharth Vijayakrishnan discusses how web servers work and compares Apache to other web servers like Lighttpd. He explains that while Apache is popular, its multi-process model does not scale well under heavy loads. Lighttpd uses an event-driven model and single process design that allows it to outperform Apache in benchmarks. It has gained popularity as a faster alternative to Apache for serving dynamic content. The document also outlines future areas of improvement for Lighttpd.