The Greensboro Family History Center's September Workshop featured Michele Doyle presenting the how and why of Citations.
The purpose of citations is to evaluate your evidence to justify the conclusions drawn, in other words, to "prove" your genealogical findings. Looking at where the information comes from, checking to make sure there are sources, being able to find that source again and evaluating conflicting information are several reasons for citing your work.
A notable concern for online records is the possibility that they will not always be available where they were originally found. FamilySearch does not own all the records found on the website, FamilySearch.org. Records are often used under contract for a designated period of time from another owner of the repository. As such the links may not always be active. To avoid this problem, copy the citation AND keep a copy of the record, at least a digital copy, if not also a paper copy.
The uncontested mentor of citations is Elizabeth Shown Mills, author of Evidence Explained, the go to resource for ALL types of citations. Elizabeth is open about citations. Although she often uses the Chicago style for genealogy works, she encourages all genealogy researchers to decide on a style and be consistent. The actual style is not as important as consistency.
Resources can be organized into 2 categories: original sources (created at the time an event happened) and indirect (created after an event happened. Sometimes a document will have both direct and indirect information. For example, a death certificate created at the time of death may contain the recent death date (direct source) and the birth date (indirect source). Primary information is recorded when the record created; secondary information was recorded later. Direct evidence is dated on a source while indirect evidence is often derived from information from several sources.
All this and more was discussed at the workshop. We all came away with a healthy respect for citations.
Some online resources: