If you’re a millennial — sorry to drop that label on you, but you are what you are — and if you are what millennials are, then you damn well know about Gak — Gak is Gaktastic, and Gak comes in many varieties. If you’ve ever read a BuzzFeed, then you’ve probably read about Gak like, maybe like six thousand different times. But I’ll bet you’ve never read about different types of Gak. So here they all are, provided for you and your enjoyment and its splendor.

1. Classic Gak

1.1 Standard Gak

First kind of Gak is pretty simple Gak, standard-issue Gak.

1.2 Gak-in-the-Dark

Second kind of Gak, glowed in the dark after exposure to light. Sent down from Heaven in 1994.

1.3 Solar Gak

Third kind of Gak was cool kid Gak only. When exposed to sunlight, Solar Gak changed from a darker shade to a lighter shade of the same color. Cool kid Solar Gak sold in purple, green, and blue.

1.4 Smell My Gak

Smell My Gak was for weird kids only. Smell My Gak smelled pretty weird, and was sold in a variety of different scents: pickles, flowers, buttered popcorn, hot dog, sunscreen, pepperoni pizza, baby powder, dirty sneakers, and vanilla ice cream. Weird kids liked Smelling My Gak.

2-3. Modern Gak and Gak Activity Sets

Yeah, in case you didn’t know Gak is back… been back since like a while ago…

2.1 Gak Pak

Gak Pak: three standard Gaks and one big container.

2.2 Gak Vac

Not real Gak, just an expensive toy vacuum–use it to suck up and spit out your Gak.

2.3 Magnetic Gak

Guess what Magnetic Gak does. Hint: comes with a metal “magic wand.”

NOTE: not sure magnetic gak was a real thing. Can't find a picture of it after five minutes of searching, so I'll say it possibly may have only been a rumor... magnetic putty in general though, that's a real thing...

2.4 Gak Inflator

Another Gak that’s more toy than Gak. Blows up your Gak like you blow up bubblegum.

2.5 Gak Copier

Just like silly putty, but just Gak, so some would say better… and requires an additional toy, so also more expensive…

2.6 Gakoids

Just people at Gak running out of ideas what to do with Gak… container for your Gak…

2.7 Gak Color Mixer

Very new breed of Gak, 2012 new breed of Gak… Mix any six Gaks, makes new color Gak

2.8 Gak Splat!

Not a good Gak…

2.9 Gak Super-Stretch

This 2013 Gak is a very, very stretchy Gak.

3.0 Mood Gak

Similar to the Solar Gak of old, but with Mood Gak color changes by way of you touching it, and returns to its original color in sunlight.

3.1 Gak Twisted

Two different colored Super-Stretch Gaks spiraled into one in one container.