Unintentional plagiarism is where someone takes someone else’s idea and thinks that they would have thought of the same thing, which leads them to use some of the same words and the person's idea as their own without properly citing or giving them credit for their work. To avoid unintentional plagiarism you should create a references page and cite any sources that you received any information from. Knowing how to properly cite sources is very important, make sure you take note of every website, book, article, etc. so that there is no way to overlook citing that source.
When in doubt cite it out!!
Hope I helped!!