几乎所有的大型应用都会有自己的用于跟踪调试的API。因为一旦程序被部署以后，就不太可能再利用专门的调试工具了。然而一个管理员可能需要有一套强大的日志系统来诊断和修复配置上的问题。

经验表明，日志记录往往是软件开发周期中的重要组成部分。它具有以下几个优点：它可以提供应用程序运行时的精确环境，可供开发人员尽快找到应用程序中的Bug；一旦在程序中加入了Log 输出代码，程序运行过程中就能生成并输出日志信息而无需人工干预。另外，日志信息可以输出到不同的地方（控制台，文件等）以备以后研究之用。

Log4net就是为这样一个目的设计的，用于.NET开发环境的日志记录包。(Almost all large applications have their own API for tracking debugging. Because once the program is deployed, it is unlikely to use a special debugging tool. However, an administrator may need a powerful log system to diagnose and fix the configuration problems.

Experience shows that logging is often an important part of the software development cycle. It has the following advantages: it can provide accurate environment application runtime, developers can find as soon as possible in the application of Bug; once in the process of adding the Log output code, the program can generate and output the log information without manual intervention. In addition, the log information can be exported to different places (consoles, files, etc.) for future research.

Log4net is a log record package designed for such a purpose for the.NET development environment.)