Baptismal and marriage records may include witnesses. What is the value of recording the names of the witnesses? How can this information be used?
Witnesses should be recorded for every event, baptisms and marriage events included.
First, these witnesses are important people in the life of the person in question. Second, the witnesses' lives intertwine in at least this one way and possibly more. Third, research into the witnesses' lives may enable you to find out more about your person.
It's too bad most genealogy software does not encourage the recording of witnesses more than they do.
Note that early versions of GEDCOM had a WITN tag. This was removed in GEDCOM 5.4 in favor of the ASSO (association) tag with the RELA (relationship) subordinate tag which can do much more than the WITN tag could do. Not all programs support it fully and import or export it well. Some programs still support the WITN tag, and some have decided to use a _WITN user-defined tag once WITN was removed. So the sad result of this is that witness and relationship information does not transfer well between programs.
A baptismal witness may have emigrated from the same region as your ancestor. I was unable to locate the point of origin for my German ancestor, but the baptismal witness for one of his children traveled on the same ship and his origin was known. This helped me connect to previously unknown ancestors in Germany.
A useful guiding principle is that you should record everything that might be useful to you later (even if you are not sure at the moment how you will use it).
You may have heard of the approach called FAN Club genealogy that emphasises research on Friends, Associates and Neighbours of your target family as a way around apparent blockages. Witnesses recorded on vital records are almost certainly in the FAN category and may be shown to be family you have not yet discovered.
An important decision is how you record the information in a way that makes it accessible to support (or to suggest) future research. The details will vary from one software package to another but most tools should allow you to choose from among these options.
1 Person + Event - Role:Witness
If you strongly suspect that the individual named has an important role in your history (for example, she is probably the bride's cousin), you might include them in your database as a distinct individual and link them to the (shared) event with the Role of Witness.
2 Event - Attribute - Witness:Name
If you are unsure of the strength of the connection between the participant and the witness (he might just be a friend from the football club), you might not want to create a new person. Then the record can be attached as an Attribute of the Event.
3 Event - Note
The disadvantage of the attribute method is that it usually creates a separate entry for each person. That may be suitable for the two people who signed the register but would be cumbersome if you have found a copy of the guest list from your grand-parent's wedding breakfast. In that case, you might attach a free-form text note to the event.
If you do choose option 2 or 3, then it is important that you remember to cross-check when other pieces of information become available. If you have entered the same name as a Witness attribute for the baptismal event of several children, then you should seriously consider whether he or she is worth upgrading to a Person entry with rich connections to the family.
Somtimes you do need to balance the desirability of recording everythinge against practicality. Should I attach the full passenger list of the ship to a migration event? Most of them are people that my ancestor probably never saw again after landing, but if a name should turn up as a marriage partner in the next generation we have prima facie evidence that the families remained in contact. Your records need to include a reminder to recheck that source even if you choose not to attach the full list.
Yes, there's great value in recording and investigating the witnesses. Witnesses for marriages, baptisms, wills etc. are often related to the primary participants. And if they're not related by blood, they may be connected in some other way that helps you trace your family history. Sometimes the connection is immediately obvious. At other times the relevance may not become clear until later in your research.
For example, my great-grandfather Thomas (Tom) Jones aged 23 married in 1893. He named his father as Thomas Jones (deceased) and one of the witnesses at his wedding was Daniel Davies, a name which hadn't come up before and didn't seem to have an obvious connection. Tom's address was 10 Rees Street, Twynyrodyn, Merthyr Tydfil.
In the 1891 census, Tom was a lodger at 9 Rees Street. And living next door at 10 Rees Street was Daniel Davies and his family (I always look at the neighbours in a census -- you never know what you'll find). So, Tom was very probably lodging with Daniel Davies at the time of his marriage. Whether there's a deeper connection, I don't know yet, but Daniel Davies is a name I'll be keeping an eye out for as I try to trace Tom's parents.
Of course, the connection may not be a personal one at all. If you're looking at the witnesses to a marriage in a Parish Register, check the names of witnesses of other marriages in the same year. You may find the same name cropping up again and again... the name of one of the church wardens, who often acted as the witness at a marriage where (for example) the groom was out of his own parish, or one of the participants for some other reason wasn't able to have a friend or relative present.
One way of cross-checking on this in England and Wales is to look at the Bishop's Transcript for the relevant year and the years either side. The entry for the marriage in the transcript won't help -- witness names weren't copied -- but the church warden had to countersign each year's transcript (at the end after the incumbent's declaration that the copy was accurate yada yada yada). So if the same name crops up repeatedly as a witness and countersigned the Bishop's Transcript, you're probably looking at a church warden.
Which doesn't of course mean there isn't another connection... Thomas James, a Church Warden in Llanfair Nant Y Gof witnessed very many marriages in his tenure, but so many of the marriages round there were cousin marriages, he was related distantly to quite a few of the participants.
This might vary, but in many cases witnesses are people with whom the parents or newlyweds are familiar with, can be family, friends etc. If they are related you might be able to find the link anyway, but this would be extra confirmation and pointer to strong relationship, if they come up again and again. It might be helpful, if there are several families in the area with the same surname and you are not sure, if they are related. This could be also useful with women who have changed their original family name (you could find out what was the old/new one from surnames of relatives involved). Also in some places baptismal witnesses would include godparents which by tradition were supposed to take care of child, if something happened to parents, it might be helpful, if parents indeed die early on