What sources are not allowed or discouraged in a research paper?

Some sources are not strictly “banned” everywhere, but many instructors discourage using things like Wikipedia, personal blogs, unverified social media posts, and outdated or non peer reviewed material as main evidence in a research paper. The exact rules depend on your course and university, but academic writing generally favors peer reviewed sources, reputable books, and official publications over informal or anonymous content.

In most research papers, the problem is not that a source exists online, but that it is unreliable, biased, or too general to support a serious argument. Here are types of sources that are often not allowed or strongly discouraged as main references:

• Wikipedia – Helpful for background and quick orientation, but anyone can edit it, and it is not considered a citable academic source. Use it only to get started, then move to primary sources and peer reviewed articles.
  
  

• Personal blogs and opinion sites – Posts on personal websites, fan pages, and informal opinion articles are usually not suitable as evidence unless you are analyzing them as data (for example, in a media study). They are rarely reviewed or fact checked.
  
  

• Unverified social media posts – Tweets, TikToks, Instagram captions, or Facebook posts are generally not acceptable as academic sources because they are highly biased, easy to fake, and often lack context. Like blogs, they can be data but not core “evidence” for most topics.
  
  

• Generic study guides and essay mills – Websites that provide pre written essays, revision notes, or assignment “help” are not academic sources. They often oversimplify concepts and may contain errors.
  
  

• Commercial websites and ads – Company pages, promotional materials, and marketing content focus on selling something, not on presenting balanced, evidence based information. They can show what a brand claims, but they should not replace scholarly sources.
  
  

• Outdated sources in fast moving fields – In areas like technology, medicine, or current policy, very old sources may no longer be accurate. You usually need recent primary sources and up to date reviews, with older material used mainly for historical context.

Even when a type of source is discouraged, it can sometimes still be used in a limited way. For example, you might quote a news article to show public reaction to an event, or use a social media post as part of your data in a qualitative study. The key is to base your main arguments on credible, scholarly material like peer reviewed journal articles, academic books, and official reports.

So, sources that are not allowed or discouraged in a research paper tend to be those that are anonymous, opinion based, outdated, or not formally reviewed, especially if you try to use them as your main evidence instead of as context or data.