FreeBSD offers advanced networking, performance, security and compatibility features today which are still missing in other operating systems, even some of the best commercial ones: – A merged virtual memory and filesystem buffer cache continuously tunes the amount of memory used for programs and the disk cache. As a result, programs receive both excellent memory management and high performance disk access, and the system administrator is freed from the task of tuning cache sizes. – Compatibility modules enable programs for other operating systems to run on FreeBSD, including programs for Linux, SCO UNIX, NetBSD, and BSD/OS. Kernel Queues allow programs to respond more efficiently to a variety of asynchronous events including file and socket IO, improving application and system performance. -Accept Filters allow connection-intensive applications, such as web servers, to cleanly push part of their functionality into the operating system kernel, improving performance. – Soft Updates allows improved filesystem performance without sacrificing safety and reliability. It analyzes meta-data filesystem operations to avoid having to perform all of those operations synchronously. Instead, it maintains internal state about pending meta-data operations and uses this information to cache meta-data, rewrite meta-data operations to combine subsequent operations on the same files, and reorder meta-data operations so that they may be processed more efficiently. -Support for IPsec and IPv6 allows improved security in networks, and support for the next-generation Internet Protocol, IPv6. Work in-progress includes support for fine-grained SMP locking in kernel, allowing higher performance on multi-processor machines, support for Scheduler Activations, allowing parallelism in threaded programs, filesystem snapshots, fsck-free booting, network optimizations such as zero-copy sockets and event-driven socket IO, ACPI support, and advanced security features such as Mandatory Access Control. FreeBSD makes an ideal Internet or Intranet server. It provides robust network services under the heaviest loads and uses memory efficiently to maintain good response times for thousands of simultaneous user processes. Visit our gallery for examples of FreeBSD powered applications and services. ( Excerpts from )