网志（英语：Blog，为Web Log的混成词），意指log on the web意即在网络上纪录，是一种由个人管理、张贴新的文章、图片或影片的网站或在线日记，用来纪录、抒发情感或分享信息。网志上的文章通常根据张贴时间（Chronological Order），以倒序方式由新到旧排列。

许多博客作者专注评论特定的zh-hans:课题或新闻，其他则作为个人日记。一个典型的博客结合了文本、zh-hans:图像、其他博客或网站的超链接、及其它与主题相关的媒体。能够让读者以互动的方式留下意见，是许多博客的重要要素。大部分的博客内容以文本为主，也有一些博客专注艺术、摄影、视频、音乐、播客等各种主题。网志是社会媒体网络的一部分。

A blog (a truncation of the expression weblog) is a discussion or informational site published on the World Wide Web consisting of discrete entries ("posts") typically displayed in reverse chronological order (the most recent post appears first). Until 2009, blogs were usually the work of a single individual, occasionally of a small group, and often covered a single subject. More recently, "multi-author blogs" (MABs) have developed, with posts written by large numbers of authors and professionally edited. MABs from newspapers, other media outlets, universities, think tanks, advocacy groups, and similar institutions account for an increasing quantity of blog traffic. The rise of Twitter and other "microblogging" systems helps integrate MABs and single-author blogs into societal newstreams. Blog can also be used as a verb, meaning to maintain or add content to a blog.