For many Americans, your genealogy search is going to take you back to England. Depending on the time period you are dealing with, this can be easy or it can be difficult.
In 1837 civil registration was mandated in England. What this means is at this time all births, marriages and death were registered with the Civil authorities. These registers can be accessed for free online at http://www.freebmd.org.uk/ . All the years are divided into four quarters so while you will not get exact dates, you will get the quarter in which the event was recorded. Once you have the information about the quarter that the event took place you can order an official certificate from the GRO (General Register Office).
A work of caution, it is easy to end up ordering a bunch of certificates for people who are not really your ancestor. Many people have the same name, Unless you have a very unique name, the possibility is high that you will make at least one mistake.
I have ordered many certificates over the years both through the mail and in person in England and I have ended up with several that are relatives but not the person I was looking for. The good news is, to date, I have never got someone who was not related to me at all. Be sure in a marriage that you find both spouses in the same quarter.
If your ancestors are prior to 1837 then the process is entirely different and I will write about that in a future post.