When a soon-to-be wife brought significant estate (eg a manor and lands) with her to a marriage, medieval custom provided that the husband held the wife’s possessions. For the most part, the husband, in turn, used the estate for the benefit and upkeep of both himself and his wife during their lifetimes.
A jointure or marriage contract signed at the outset would provide for her continued maintenance in the event of the husband’s death before the wife's. This commonly took the form of specifying her income and from which premises (properties) that income should arise after his death. Only after her demise would the same estate pass to the eventual heir - the eldest son, for example. Otherwise, the inheriting son or daughters might take control of the entire estate, including the widow’s home and income, leaving the widow destitute after her husband died.
In the not-so-unlikely event the widow had no jointure, she might pursue her dower rights. Her right to a dower served the same purpose as a jointure. The lord of an estate could divide his estate into 'thirds', one of which was the dower. Thus the widow could claim the income from up to one third of the deceased lord's estate, with right to collect rents direct from the occupants of the lands. The escheator often declared the widow's dower rights to the deceased's estate at the inquisition post mortem (IPM). An example occurred in 1276 for Marjory, widow of Lord Eustace de Watford.
Sometimes the lord of the manor left specific provision for his widow's maintenance. Typically, he viewed this as more generous than anything the widow would obtain should she pursue a dower. To protect his estate from a 'mischievous' widow, the same lord might stipulate that in the event she took legal action to increase the allowance, then the said specific provision ceased and became null and void.