This is an ongoing series on starting your family history research in 10 very basic steps. The steps so far are:
Step One: Start with yourself.
Step Two: Find out what has already been done.
Step Three: Choose a reasonable goal
Step Four: Start educating yourself
Step Five: Seek a Teacher or Mentor
Step Six: Use The Family History Guide
Step Seven: Choose a place to record your research
Now I will move on to Step Eight:
Step Eight: Add Sources to Your Entries in Your Family Tree
A source is a description of the place where you obtained the information you add to a family tree. If you fail to provide a source for your information, the next person who comes along and views what you have entered, will very likely have to do all your research over again to verify that your conclusions were correct. From my own position, I am forced to doubt any information that does not give a source for that information. Initially, much of the information in the FamilySearch.org Family Tree lacked source citations. More recently, millions of sources are being added to the Family Tree every month. For example, if you have a Bible in your possession that lists family members and their birth, marriage and death dates, that Bible is your source. Because the Family Tree also allows the users to add Memories which include copies of documents, you should also add in any copies of documents. This would include making a copy of the pages from your family Bible or other record. Although you can link to a copy of a document from another website, it is a good idea to provide digital copies of any documents you have in your personal possession.
There are entire books written about the "proper" way to cite your sources (the source is the place where the information was found and the citation is the way the source is recorded). Unless you are planning to publish your research in a genealogical publication, the format of the citation is not a crucial issue. What is the issue is whether or not you have adequately described how someone would be able to find your source and verify your information.
The FamilySearch.org Family Tree gives you a generic form for entering your own source information. However, when you add a source to the Family Tree from another programs such as Ancestry.com, then the source is the document you found with the information about your family, but where you got that information is Ancestry.com (or whatever other website).
Every piece of information you add to the Family Tree should have a source citation. If you find that some of your ancestors do not have source citations, it is good idea to add in all the Record Hints and also add any other documentation you can find to support the names, dates and places.