See the previous article, "Probate records - more than just wills."
When a person died, their estate had to be administered. The first step in this process was to appoint an administrator. In Maryland, the county Orphans Courts held jurisdiction over the appointment of executors and administrators.
Testate estates are those in which a will was created. Most last wills and testaments name the desired executor. The executor was the person that the decedent wished to have execute his will. In most cases the executor was approved by the probate court, but occasionally this did not happen. Sometimes heirs may contest the appointment of the executor, in which cases there may be notes in the probate court proceedings. The executor named in the will may also renounce the executorship, if they did not wish to act in this capacity. In these cases another administrator may be recommended or appointed.
When an administrator had to be appointed over a testate estate, he would be called an "administrator with will annexed," rather than an executor.
In intestate estates no will was created, and therefore no executor was named. In these cases, the probate court would have to appoint an administrator. The surviving spouse or one of the elder sons was often appointed. Again, records related to the appointment (sometimes including the relationship to the decedent) would likely appear in the probate court proceedings.
Once an executor or administrator was appointed, most states, including Maryland, required a bond to be filed. These are called simply "testamentary bonds" or "administration bonds." Though these bonds are often rather short documents, with a lot of boilerplate language, they can still contain significant clues in your research.
A common bond would consist of language similar to the following:
Know all men by these Presents that we Cloe Walker Widow, Thomas Owen & John Wynn all of Prince George's County Maryland are held and firmly bound unto the Right Honourable Lord Proprietary of this Province [or later, "unto the State of Maryland"] in the full and just sum of Two hundred Pounds ...
The condition of the above obligation is such that if the above bound Cloe Walker administratrix of all and singular the Goods and Chattels, Rights & Credits of Richd. Walker late of Prince Georges County deceased ...
Notice that the bond names three (or more) people right at the beginning. The first of these names, as is revealed later in the bond, is the name of the executor or administrator of the estate. The other names are the sureties of the bond.
Sureties are like co-signers on a loan. They bind themselves to also pay the penalty if the administrator does not faithfully perform the prescribed duties. In most cases these bonds hold quite large financial penalties, so acting as a surety on a bond is far more serious than, say, witnessing a deed. This was not a position that one would undertake for a stranger.
In many cases, the sureties on an administration bond (or any other bond) were family members or close associates. When the widow served as the administrator, the sureties on her bond were almost certainly male family members, including brothers-in-law or stepfathers. Diligent research on these sureties may reveal the maiden name of the widow, where no other source for this information may exist!
 Prince George's County, Maryland, Register of Wills, Administration Bonds (Original), Box 17, folder 44, Richard Walker estate (1769); MSA C1147-17, MdHR 8925-17-44; Maryland State Archives, Annapolis.