For general knowledge and quick facts:
* Wikipedia: A free, online encyclopedia with articles on a vast array of topics. It's a great starting point for basic information, but remember to always check the sources cited within each article.
* Britannica: Another well-respected encyclopedia with comprehensive coverage. While not completely free, they do offer some free access.
* Khan Academy: A non-profit organization offering free educational resources, including video lectures and articles, across a wide range of subjects.
For specific subjects:
* Subject-specific websites: There are websites dedicated to nearly every field of study. For example, NASA.gov for space exploration, the National Geographic website for geography and natural science, and the CDC website for health information.
* Textbooks: While they can be more in-depth than the resources above, introductory-level textbooks can provide a solid foundation in a specific subject.
* Online courses: Many universities and institutions offer free or low-cost online courses, which can provide structured learning experiences. Platforms like Coursera and edX are great places to find these.
For research and academic purposes:
* Academic databases: These databases, such as JSTOR and Google Scholar, offer access to scholarly articles and books.
* Library catalogs: Your local library's catalog can help you find books, journals, and other resources.
Ultimately, the best source for you will depend on your needs. Remember to always evaluate the credibility of any information you find online and be sure to cite your sources.