I started and deleted responses several times. I'll try to keep this one brief.
Free? Yes and no. Remember free does not mean easily accessible.
Many records are public and available for "free" to anyone who wants to see them but they may not be available for free "online".
For example, census records thru 1940 are public. An index to a particular census may be available for free online but the actual record (particularly a scanned original) may only be available through Ancestry (pay) or the LDS Church (free with free registration/account). By setting up a free account with Family Search (the LDS) you can see indexes of the census and often transcriptions of the census records. If you want to see the actual scanned document you will need to go to an LDS Family History Center and use their terminals to see the original record.
Other documents like Wills, marriage records, birth/death records, and deeds may appear on indexes created by genealogists and those indexes are typically free to use. However, to see the original Will or deed it is often necessary to either visit the county clerk's office or send someone to make you photocopies of the document. It's a public record but they aren't all digitized so you have to pay one way or another to get that public information.
If you have specific questions about this you can PM me. My wife is the family genealogist and she works with this sort of thing daily.