On Wikipedia, bias means something different from what it means elsewhere. We say content is biased if it doesn't have a neutral point of view, which means representing fairly, proportionately, and, as far as possible, without editorial bias, all the significant views that have been published by reliable sources on a topic.
Similarly, reliable sources means something specific on Wikipedia. Reliable sources have characteristics such as editorial control, a reputation for fact-checking, and independence from their subject. They can have a bias but still be reliable; we just have to attribute their views and not give them too much weight. You can see a list of popular sources and how the editor community has evaluated their reliability at Wikipedia:Reliable sources/Perennial sources. Click on this footnote to see how these policies can be challenged.[a]
Editors have evaluated reliable sources and have determined they are generally critical of Trump. His article reflects this. We can't do much with a simple claim of bias; we need evidence the article doesn't have a neutral point of view. Click on the footnote to see some ways this can be done.[b]
If you start a discussion based on this, ensure your proposal is specific, refers to the policies and guidelines it is based on, and is supported by reliable sources.[c] You need to assume editors are acting in good faith. They will assume the same of you. Civility is very important on Wikipedia; your comments should create a pleasant editing environment. If a consensus forms, the article will be changed.
Wikipedia has some resources to help you further:
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