What is a 'tactical flashlight'?

Maybe ones that you can plop into one of those flashlight mounts that you put on those picatinny rails.

I don’t watch those commercials because the flashing hurts my eyes, but if you listen, their brightness is greater, and they are tough enough to withstand a lot more abuse.
Me, I’m happy with the assortment I have, which includes a headlamp. Needing my hands to walk (crutches or walker) makes this headlamp a must. It is adjustable to focus a beam to a specific area, or widened, to reveal more surroundings. I got it for under four bucks on ebay.
Sometimes I wear it around the house at night to avoid flipping lights as I prowl the kitchen, bathroom, whatever.
Purchasing such things are according to individual needs.
If all you ever need them for is to check the power box when the lights go out, a dollar store penlight works fine.
If you camp or hunt where you might encounter night predators, get the tactical deal. It would blind them and give you a possible out.

I have one. They are very, very bright. The idea is that if you are attacked at night, you can shine the light in the attacker’s eyes. It will blind them momentarily. Then hopefully you can run away.

(The NSA clearly doesn’t want me giving you this information, because I typed in an answer than then it disappeared. They may have mind-controlled my cat and got it to select all and hit the space bar, but Undo didn’t work, so it must be their black ops cyberwar unit.)

It is marketing crap, but not entirely.

It makes people think they “are tactical” or have some advantage when they have one.

In practice, they may have some uses. They’re generally crazy bright and have a “strobe” feature that (in the imagined situation where it is dark and evil minions want to harm you), you can use this not just to see people (the better to e.g. shoot them), but also to blind them , startle them, disorient them, etc.

(Of course, they may not figure that people such as my friends used to use strobe lights in the dark when playing “savage melee combat”, in which case we may be fairly used to fighting during a strobe effect, and it may actually trigger us to enter a battle fugue state…)

Others have an infrared mode, so with the right filtered vision gear you could also see people without them seeing you. With both types, maybe you could massacre a room full of goons as demonstrated pretty well by Hit Girl in Kick Ass as seen in the scene where she attaches a tactical flashlight to her pistol, uses it to blind/confuse people while shooting them, then the scene shows how it can also give away your position and draw attention, but then she sets it down pointed at the gunmen, getting them to just see (and continue to shoot at the flash), and uses that and cover to get around behind them and kill them.

Or you could get a Maglight and use it as a club to bash people.

I bought one this year.
They are insanely bright, and will momentarily blind anyone you shine it at.

I have several I use, once you get a real bright flashlight like that you want to toss your old ones. I have a waterproof one I use for crabbing at the beach. Several others for just general use. Other than being tacti-cool looking they’re just really bright usually with a cree LED, strobe function and the ability to focus the beam. The “tactical” part is mostly marketing.

It’s OD green or black, not chrome, and I always thought a tactical flashlight was one of those 90 degree jobs that you can hook to the front pocket of your combat coat so it will shine on the map you’re trying to read with both hands, or to stand on one end in the outhouse to see where the hole is while you’re trying to hit it.

In general, “tactical” equipment of this type means that it has defensive (or offensive, depending on your mindset) capabilities:
1. Tactical flashlights are, in general and as others have already said, very bright, almost to a point of pain when looking directly into the beam. So in that way they can temporarily blind and disorient or disable an attacker.

2. They generally also have a strobe capability, which is good for signalling, and also for disorientation of an attacker.

3. They frequently have physical characteristics built into the instrument itself, such as a hardened body (more rugged than the old-fashioned D-cell flashlights of old, with their cheap, thin-wall construction that was prone to denting at a light touch or short drop) and a “castellated” lens bezel, which can be used – even with very small models – to strike an attacker and cause injury, while affording some protection to the lens as well.

4. In addition to all of that, they may have features such as quick attachment to a rifle’s picatinny rail, as noted above, or clips for attachment to a backpack, for example, and other features not seen on “normal” flashlights, including a “moonglow” brightness setting which may be good for a user to see a few feet ahead in the dark, but does not give away a position beyond a few meters.

I have one. It will blind you!

“Tactical” means it is painted black and they sell it to people with ninja/action-hero fantasies.

Its a very bright flashlight—you can light an entire 70×40 attic very well with one.

I don’t care for the strobe and SOS features.