Halachos of the Daf - Bava Basra 76

(Choshen Mishpat Siman 197, 198)

As mentioned previously, in order for an object to be transferred into someone else’s ownership, a kinyan is required.

Mesirah means that it was given over. The buyer simply holds onto the object, and without lifting or pulling it, he has acquired the object, via the kinyan of mesirah.

Aside from animals, which can be acquired either through mesirah or meshicha – pulling, mesirah is a valid kinyan, only when one can’t make meshicha. An example would be, if one were to acquire a ship, which can’t be dragged. All other movable objects can not be acquired through mesirah.

Mesirah can only be valid in a Reshus Harabim, or a property which is not owned jointly by the seller or the buyer, nor do they have permission from the owner to enter.

In order to acquire an animal via mesirah, the buyer can do any of the following:
Hold onto its; leg, hair, caddle, load, muzzle, or bell.

The seller need not actually hand over the object, rather as long as the buyer holds onto the object in front or on the command of the seller, the mesirah is valid.