Communal area cleaning is the cleaning of a shared space that is partially, or fully used by separate occupants. This type of setting is familiar with close communities that live or work around each other, for example, it is not uncommon for multiple families or occupants to share a large kitchen area or bathroom, or even have a shared living room. In some office blocks there are shared meeting rooms too. But there are often times, within this setting, that it becomes difficult to decide who should clean which areas, which can lead to a problem.
Leaving communal areas for a long time without regular cleaning will obviously cause it to get dirtier quicker than if a single occupant used it, that is down to just more bodies being in one space. This can become a hygiene hazard and can cause people to fall ill, or just cause it to be an unpleasant place to be in, because of potential smells, dirt and dust.
Of course, nobody who uses one of these settings would like that to happen, one of the big parts of using a partially or fully shared space is that there is a community feel and a happy, relaxed atmosphere to keep things light for everyone. So having the shared area being an unhealthy place to be in can really wreck that atmosphere. Many landlords, businesses or occupants decide to get a cleaner for that specific area of the building.