The Moon moves through eight phases every cycle, and each one carries a different energy for manifestation, action and release. Explore all 8 here.
The Moon changes sign every couple of days, but it only completes a full cycle once a month — which makes the phase the most reliable rhythm in lunar practice. Phase tells you where you are in a process: starting, building, peaking, or letting go. If you only track one lunar thing, track this.
The four waxing phases are for beginning, refining and pushing a project forward. The full moon is the visibility point, where results show up whether you are ready or not. The four waning phases are for reviewing, editing, forgiving and clearing space. Time an intention to the new moon and review it at the full moon and you have a complete monthly loop. For the sign the Moon is passing through right now, see moon signs.
Roughly three and a half days each, since the whole cycle takes about 29.5 days. The exact moment named in an ephemeris — the exact new moon or exact full moon — is a single point in time; the phase itself covers the days around it.
It is the most visible one. Full moons amplify what is already there, which is why they feel dramatic — but they are better for revealing and completing than for launching something new. For starting, the new moon is the stronger window.
No. The phase describes the timing, not the person. How strongly you feel it depends on your own chart — particularly your moon sign and whether the current moon is touching your natal placements — so two people can experience the same full moon very differently.