Web服务器（Web Server）指 ：
- 软件。运行在 Web服务器上的能够用来协助发布Web信息的软件，此时，等同于 Web服务器软件（Web Server Software）
日常生活中提到的Web服务器（Web Server）一般都是指 第2种意思，即Web服务器软件（Web Server Software）。Web服务器软件有很多，主流的有：Apache、IIS、nginx、GWS 以及lighttpd。以下内容由笔者从wikipedia整理汇总.
The Apache HTTP Server, commonly referred to as Apache , is web server software notable for playing a key role in the initial growth of the World Wide Web. In 2009 it became the first web server software to surpass the 100 million website milestone.Apache was the first viable alternative to the Netscape Communications Corporation web server (currently known as Oracle iPlanet Web Server), and has since evolved to rival other web servers in terms of functionality and performance. Typically Apache is run on a Unix-like operating system.
IIS，formerly called Internet Information Server – is a web server application and set of feature extension modules created by Microsoft for use with Microsoft Windows. It is the most used web server after Apache HTTP Server: As of January 2011, it served 21.00% of all websites on the Internet and 16.22% of the one million busiest websites on the Internet.IIS 7.5 supports HTTP, HTTPS, FTP, FTPS, SMTP and NNTP. It is an integral part of Windows Server family of products, as well as all editions of Windows Vista and Windows 7, although some features are not supported on client versions of Windows. IIS is not turned on by default when Windows is installed.
Nginx (pronounced “engine-x”) is a lightweight, high-performance Web server/reverse proxy and e-mail (IMAP/POP3) proxy, licensed under a BSD-like license. It runs on Unix, Linux, BSD variants, Mac OS X, Solaris, and Microsoft Windows
Google requires large computational resources in order to provide their services. The technological infrastructure behind Google’s websites, as presented in the company’s public announcements have made up a new web server called GWS. Most of the software stack that Google uses on their servers was developed in-house. It is believed that C++, Java, and Python are favored over other programming languages. Google has acknowledged that Python has played an important role from the beginning, and that it continues to do so as the system grows and evolves.
lighttpd (pronounced “lighty”) is an open-source web server more optimized for speed-critical environments than common products while remaining standards-compliant, secure and flexible. It was originally written by Jan Kneschke as a proof-of-concept of the c10k problem – how to handle 10,000 connections in parallel on one server,but has gained worldwide popularity.