Why are there 28 days in the Moon's calendar?

The Moon's calendar, often referred to as the lunar calendar, is based on the phases of the Moon, which cycle approximately every 29.5 days. However, many lunar calendars, such as the Islamic calendar, consist of 12 months with 29 or 30 days, leading to an average of about 28 days in each month when simplified. This system aligns with the Moon's visibility and phases, making it practical for tracking time. Additionally, a 28-day month fits neatly into the lunar cycle, making it easier for traditional cultures to organize their activities around the Moon's phases.