A novelty cup, see for example here, appears black when cold. When hot liquid is poured into it, the black changes to white and the previously concealed writing (underneath, so to speak) becomes ...
If one would type on a computer on Shabbos would he be ovar an issur d'oraisa in regards to the malacha of writing? (The other malachos involved aside for a moment.) Is there any room to say this ...
In order to transgress "writing" (כותב) on Shabbos, (m'd'oraysah) one must write two letters. (See for example here.) Why is this so? Shouldn't writing anything still be considered writing? For ...
If I am teaching myself a foreign language as a leisure activity, may I write in a workbook on chol hamoed, for the purpose of retaining my knowledge? If I haven't begun, may I start the new language ...
Is typing allowed on Chol Hamoed? Does it make a difference if whatever is typed will be printed afterwards?