White wire that carries the unbalance load between two hot (ungrounded conductor) A neutral must be serving two ungrounded conductors (a.k.a. hot conductor) that read 240 volts between those two ungrounded (hot) conductors.
White wire that serve only one ungrounded conductor (a.k.a. hot conductor)
Those ungrounded conductors (a.k.a. hot conductors) installed between the light box and any switch box.
Note: A switch leg does not contain a grounded leg (a.k.a. neutral) or true neutral conductor but contains only ungrounded (a.k.a. hot) conductors whether constant hot conductor feeding the switch power or intermittent hot conductor feeding the light from that switch.
Notice this switch leg is either an ungrounded conductor (a.k.a. hot conductor) or an intermittent ungrounded conductor (a.k.a. intermittent hot conductor) energized with power only part of the time while the switch is in the on position.
Also notice that a switch leg is a set of ungrounded conductors (a.k.a. hot) that may contain a white ungrounded conductor (a.k.a. white wire used as a hot wire using an exception in the NEC allowing a white conductor to be hot but only if used as a switch leg without a grounded conductor (a.k.a. neutral or grounded leg)
A switch leg can not contain a grounded leg (a.k.a. neutral) or a true neutral at all. If this set of wires were to contain a grounded leg (a.k.a. neutral) or true neutral then this set of wires would not be a switch leg but would be called a normal power cable.
(Any color in rainbow but white, gray, bare or green) serving a receptacle or any other electrical device is a ungrounded leg (a.k.a. hot conductor). That white wire serving a220 volt oven with two ungrounded conductors (a.k.a. hot wires) measuring 240 volts between the two ungrounded conductors (a.k.a. hot wires) then that white wire is a true neutral (a.k.a. neutral conductor.)
The term ground is a generic term that may mean neutral, equipment grounding conductor, earth, center tap of a transformer or two pole generator winding. The term ground is too generic in meaning to be properly used in discussions of electricity it may mean too many different things.
That hot wire attached within and coming from the light fixture itself would be the ungrounded fixture wire (any color in the rainbow BUT white, gray, green, or bare)
That grounded wire attached within and coming from the light fixture itself would be the ungrounded fixture wire (white or gray).
That wire attached within and coming from the non-current carrying metallic case of that light fixture would be the equipment grounding fixture wire (green or bare).
In general household 120v circuits the three wires used when speaking in politically correct terms are: ungrounded conductor, grounded leg, and equipment grounding conductor. To the layman, these wires should be recognized as the true politically correct electrical terminology that are mentioned and identified in the National Electrical Code book:
The grounded leg (a.k.a. neutral) (white or gray) and the equipment grounding conductor (bare or green) is only electrically married on the line side (before main disconnect or breaker) of the main service panel or within that main service electrical panel only. Any grounded conductor (a.k.a. white or gray neutral conductor) and any grounding conductor (a.k.a. green or bare equipment grounding conductor) are required to be completely separate conductors without ever touching each other everywhere else in the house that is electrically downstream of the inside of the main service rated panel.
In the electrical panel, the grounded leg (conductor) (a.k.a. neutral) or true neutral, and the equipment grounding conductor may be intermixed and electrically connected from the power company’s point of attachment at the weather head to and including within that main service rated panel, and the equipment grounding conductors are also electrical connected to the metal panel frame or metallic casing itself and must have a connection to earth ground by a grounding electrode system (thru a driven metallic rod or made electrode driven into the ground). A metal water pipe must be that primary contact to earth from that main service rated panel but only if that metal water pipe is indirect contact with the earth for at least 10’.
The ungrounded conductor (a.k.a. hot conductor) (any color in rainbow BUT white, gray, bare or green) gets its name because it has no electrical connection to the ground on the earth except through an electrical load that is doing work produced by electricity.
Electrical current can only find its way from an ungrounded conductor to a grounded conductor and finally back to the center tap of the supply transformer by passing through an electrical appliance or other electrical device usage performing some type of work produced by that flow of electricity.
Any other current flowing from an ungrounded conductor to a grounded conductor that is not flowing through an appliance or other electrical product producing work would be considered an uncontrolled current flow to the grounded system that would be creating what is called a shorted circuit or dead short. This shorted circuit or dead short would cause an over current device (a.k.a. fuse or breaker) to trip quickly due to what is called an interrupting rating of your over-current device (a.k.a. fuse or breaker), otherwise if this interrupting rating action of your fuse or breaker would fail, then the wires would fry and burn causing a fire or meld down of your conductor.
The equipment grounding conductor is required to be attached to the metal frame of the electrical appliance /devices. During the event of an electrical /electronic failure within the device any current that is flowing to the metal frame of the device is intended to be directed back to the electrical panel through this low impedance electrical path of that equipment grounding system and this dead short flow of current on that equipment grounding conductor back to that main panel and then to the center tap of the serving transformer and grounding electrode system serving your home is intended to blow the fuse or trip the breaker.
Polarized plugs are designed to ensure that the ungrounded conductor is always connected to the desired section of the appliance or other electrical device most insulated from any non-current carrying metal of that electrical device, and the same intent holds true of the grounded conductor being insulated from the non-current carrying metallic parts of that appliance or electrical device.
Things like light sockets, if you were to look inside the light socket with no light bulb screwed in, you will see an inside center electrical contact tab, and then a metal threaded outer contact encircling that center contact tab. The ungrounded conductor (a.k.a. hot) (likely the ungrounded switch leg) (a.k.a. intermittent hot) would be connected to that inside center contact being most insulated from non-current carrying metal of the fixture, and then the grounded leg (a.k.a. white or gray neutral) would be connected to the outer threaded metal screw contact that maybe more exposed to accidental human touch. Now the act of screwing in a new light bulb should go without a flaw even if you accidentally touch the threaded metal part of the bulb because it was ensured that the grounded leg (a.k.a. white neutral conductor) was connected to the more exposed metal threaded shell where your bulb screws in that you might accidentally touch.
Lets say someone made a mistake, and incorrectly reversed the wiring connections, you would then have an ungrounded switch leg (a.k.a. hot) connected to the threaded metal outer ring, with the switch on and then you accidentally rub against that metal threaded part of the light bulb while installing it, you would then present a dangerous current to yourself especially if that current finds a way thru you to path to earth ground or center tap of that serving transformer as ground.
Some people feel if it works, then it must be right, I mean it turns on, I must have did it right, but is it right, is it safe? The above should help you to make that decision concerning your electrical wiring.