Many states are adding vital records information to their state websites. As an example, today I looked at the Massachusetts Archives pages posted under the name of William Francis Galvin, Secretary of the Commonwealth. My ancestors lived in Plymouth, Massachusetts for almost 300 years and so I hoped to find information about the family. Success! When I searched for just deaths associated with the Drew surname, I received 3 pages of records from the mid-1800's through the early 1900's. Almost all of the names were in my database and for many of them, this is the only source of their death years that I have in my records.
Other states have posted similar pages on their websites. To find them, search for them using various search terms in your search engine, such as Massachusetts+Vital+Records or other similar terms. I've already talked about finding death records on state archive sites on this blog and those listings let you view actual death certificates. Most states don't post the death certificates but rather have index listings of births, marriages and deaths.
Be sure to fully explore the site for other information that has been listed about historical records for the state. Once more, we'll look at the Massachusetts website. They have posted a page that describes the types of records that have been created in the state along with sample images of the records. This information is extremely useful to researchers because the researcher now knows the types of records that can be found, the years covered by the records and where to find or obtain copies of the original records in that state.
Since I've mentioned indexes, the question arises --- Are index listings equivalent to primary source records? Well, technically no, they are not. You want to secure copies of actual primary source records to generally assure your records are correct, but the index information will certainly point you to the town, year, volume and page numbers of the primary records. So, by all means, use them as part of the sourcing of your data.
Roots TV has some very good training videos about sources that are worth review by any family history researcher. Take the time to watch at least some of them to help you correctly record and establish the quality of your source information. The longer you are involved in research, the happier you'll be that you recorded your sources accurately from the start (or from today on).