→What is a Bosis?
==What is a Bosis?==
# An object upon which [[Muktzeh]] was left intentionally from before [[Shabbat]] and one intended that it stay there as [[Shabbat]] entered (during [[Bein HaShemashot]]), the object becomes a Bosis. <ref>Kitzur Shulchan Aruch 89:1</ref>
# If muktzeh was placed on an object for part of Shabbat but was going to be removed before the end of Shabbat that object is a bosis.<ref>Rashba Shabbat 51a s.v. ha, Rashi</ref> Some Ashkenazim hold that it isn't a bosis unless one intended to leave it there for all of Shabbat.<ref>Baal Hameor
* Rashba 51a asks how the Baal Hameor could say that it isn't a bosis if one intends to remove it on Shabbat since every candle is like that since it is going to go out. The Rashba beitzah 2a s.v. ubet answers for the Baal Hameor that since one couldn't extinguish it during Ben Hashemashot it is a bosis even if one knew it wouldn't be a bosis for all of Shabbat. Alternatively, a candle is muktzeh machmat isur and not a bosis. See Shaarei Muktzeh p. 291 for explaining the Rashba.</ref>
# One may not move a Bosis on [[Shabbat]] even if one needs its place or to use it for a permitted use. <ref>Kitzur Shulchan Aruch 89:1</ref>
# A purse which is made to hold money if there’s no money inside is considered a [[Kli Sh’Melachto LeIssur]] and so if there’s a key inside one may open it to take out the key. <Ref>Shemirat [[Shabbat]] KeHilchata 20:16 </ref>
# If someone places an item on someone else's non-muktzeh item it doesn't make it a bosis unless he had permission to do so.<ref>Tosfot 44b s.v. yesh, Shitah LRan 44b s.v. lo yichda, Ritva 44b s.v. lo yichda. The Ritva explains that if someone places a muktzeh on top of non-muktzeh it doesn’t become a bosis because it is considered like it was forgotten there.</ref>