In deliberative bodies a second to a proposed motion is an indication that there is at least one person besides the mover that is interested in seeing the motion come before the meeting. It does not necessarily indicate that the seconder favors the motion.
The purpose of requiring a second is to prevent time being wasted by the assembly's having to dispose of a motion that only one person wants to see introduced. Hearing a second to a motion is guidance to the chair that they should state the question on the motion, thereby placing it before the assembly. It does not necessarily indicate that the seconder favors the motion.
The seconder may state "I second the motion" or "second" without first being recognized by the chair. They may remain seated but in larger assemblies, except in those where nonmembers may be seated in the hall, the seconder should stand. After hearing a second, the chair then states the question and the motion is placed before the assembly for discussion.
After a motion is proposed, if the motion requires a second and none is immediately offered, the chair of the body will usually ask, "Is there a second?" If no second is obtained within a few moments of proposing the motion, then the motion is not considered by the assembly, and is treated as though it was never offered. Such a motion may be introduced again at any later time.
If a motion which requires a second does not receive one, but is discussed or voted on anyway, it is too late to object to the motion on the grounds that a second was not offered. This is because the purpose of the second has been fulfilled: the assembly is obviously willing to consider the motion.
A second may be withdrawn if the motion is amended by the maker of the motion before it has been stated by the chair. Demeter's Manual states, "The seconder can also withdraw his second after the Chair has stated the question and before it is voted on, if the body permits it either by silent consent, or by majority vote if put to a formal vote."
Mason's Manual states that "Parliamentary practice in American governmental bodies does not require seconds to motions, and in Parliament itself, where the practice of seconding motions originated, they have not been required for more than a century."