YouTube, a video sharing platform, has faced various criticisms over the years, particularly regarding content moderation, offensive content, and monetization. YouTube has faced criticism over aspects of its operations, its recommendation algorithms perpetuating videos that promote conspiracy theories and falsehoods, hosting videos ostensibly targeting children but containing violent or sexually suggestive content involving popular characters, videos of minors attracting pedophilic activities in their comment sections, and fluctuating policies on the types of content that is eligible to be monetized with advertising.

YouTube has also been blocked by several countries. As of 2018, public access to YouTube was blocked by countries including China, North Korea, Iran, Turkmenistan, Uzbekistan, Tajikistan, Eritrea, Sudan and South Sudan.

Controversial content has included material relating to Holocaust denial and the Hillsborough disaster, in which 96 football fans from Liverpool were crushed to death in 1989. In July 2008, the Culture and Media Committee of the House of Commons of the United Kingdom stated that it was "unimpressed" with YouTube's system for policing its videos, and argued that "proactive review of content should be standard practice for sites hosting user-generated content". YouTube responded by stating:

We have strict rules on what's allowed, and a system that enables anyone who sees inappropriate content to report it to our 24/7 review team and have it dealt with promptly. We educate our community on the rules and include a direct link from every YouTube page to make this process as easy as possible for our users. Given the volume of content uploaded on our site, we think this is by far the most effective way to make sure that the tiny minority of videos that break the rules come down quickly. (July 2008)

In October 2010, U.S. Congressman Anthony Weiner urged YouTube to remove from its website videos of imam Anwar al-Awlaki. YouTube pulled some of the videos in November 2010, stating they violated the site's guidelines. In December 2010, YouTube added the ability to flag videos for containing terrorism content.

In 2018, YouTube introduced a system that would automatically add information boxes to videos that its algorithms determined may present conspiracy theories and other fake news, filling the infobox with content from Encyclopædia Britannica and Wikipedia as a means to inform users to minimize misinformation propagation without impacting freedom of speech. The Wikimedia Foundation said in a statement that "neither Wikipedia nor the Wikimedia Foundation are part of a formal partnership with YouTube. We were not given advance notice of this announcement."

In the wake of the Notre-Dame fire on April 15, 2019, several user-uploaded videos of the landmark fire were flagged by YouTube' system automatically with an Encyclopædia Britannica article on the false conspiracy theories around the September 11 attacks. Several users complained to YouTube about this inappropriate connection. YouTube officials apologized for this, stating that their algorithms had misidentified the fire videos and added the information block automatically, and were taking steps to remedy this.

To limit the spread of misinformation and fake news via YouTube, it has rolled out a comprehensive policy regarding how it plans to deal with technically manipulated videos.