The Torah commands us to dispose of all of our ĥametz before Passover. The biblical prohibitions on eating or benefiting from ĥametz begin midday of the 14th of Nissan, but the Sages extended these prohibitions. Consequently, benefiting from ĥametz becomes prohibited an hour before midday, while eating it becomes prohibited two hours before midday. The exact times can be found in standard Jewish calendars.
According to Torah law, one may dispose of ĥametz either by mentally nullifying it (renouncing ownership) or by physically destroying it. However, to make absolutely certain people would dispose of their ĥametz, the Sages required doing both. In practice, the way we dispose of ĥametz consists of four stages: searching for ĥametz (bedikat ĥametz) on the night of the 14th, nullifying it (bitul) that night, destroying it (biur) the following morning, and nullifying it again, more comprehensively, that morning. We will elaborate in the next two sections.
There are two more ways for a person to dispose of ĥametz: by selling it to a non-Jew (section 8 below), or by removing it from the home and declaring it ownerless. These methods work because the prohibitions apply only to ĥametz we own.
