Specific tags like: blue_body, white_scales, yellow_eyes, fangs, claws, horns. For example.
Those always made me curious, do people actually use them when searching? xD

I guess it's only optional or complement when you have no idea what else you need to tag.

Sometimes, it's all I remembered of an image...

The tags of e621 are, of course, existing for searching.
Imagine ...... a situation where you want or have to find certain post(s) for some reason.

You'll be able to use any tags as long as you can recall about its features, even if you can't recall everything.
In contrast, Tags are also useful for excluding by using minus-signs. Such as -chicken.

As a matter of fact in the past, with these features, I have successfully responded to a request to "Find a certain video".
See? We never know for whom the tags are serving their purposes, do we?

I use it for finding characters i don't know/have a name, or i just don't remember. I also use them sometimes for specificity, and basically lowering the ammount of stuff you need to go through for specifics.

It's helpful for people trying to find specific images they vaguely remember. It's also incredibly simple to make a bigger tag list this way, since characters tend to be subject to multiple colored_feature tags and each of those implies things like colored_body, horns, etc.

I think so. Some people have preferences for fairly specific features. Or maybe they're trying to find images similar to a specific character.

benjiboyo said:
I also use them sometimes for specificity, and basically lowering the ammount of stuff you need to go through for specifics.

If I had to take a guess though, this is probably their main use. To support people's main search tags.

tags have 3 general usages
browsing: using tags to just have a bunch of posts to look at
blacklisting: using tags to avoid seeing posts you don't want to see
searching: using tags to find a specific post based on elements contained within

some tags are more useful for one use more than another. users probably aren't browsing or blacklisting the <color>_body tags very often but they're still useful when trying to find a specific post.

Of course. When I search for references, especially when I need something specific, I use those types of tags.

eeveesbeingassholes said:
Specific tags like: blue_body, white_scales, yellow_eyes, fangs, claws, horns. For example.
Those always made me curious, do people actually use them when searching? xD

Not really, I don't think so. I think people tag those because pure object-based, "bulk" tags are easiest to identify and remember when tagging. You can spot what those tags describe very easily with your eyes, and they don't require much special tag awareness or research (i.e., don't need to read wikis, don't need to resolve tricky decisions, fewer qualitative decisions (size, sharpness), low English skill, etc), so anyone can tag them. I consider those tags lower quality. They usually fill out tag lists without really telling users something they don't know nor help users find posts. Busywork. These obvious tags also make tag lists harder to read and spot the more important tags.

Ideally, these tags help users find posts when saucenao doesn't work (e.g., a dog with pink hair and blue eyes) and potentially find more posts with a character but missing their name or perhaps find an unknown character's name tagged in other posts. In practice, this is very inconsistent, often requires several search attempts, and you may still not recognize your desired result out of a hundred thumbnails. For this to work, basically every post on the site needs to have thorough and consistent object-based tagging, which is extremely unrealistic. Thus, many years ago I came to the simple conclusion that every tag is "undertagged" because anything less than perfect is undertagged.

Having said that, I think there's more value in tagging what I call the "trim" tags (e.g., claw color, eye color, nose color, hair color, genitals color, etc) since they are confined to consistent locations (e.g., green claws vs black spots) and they do a decent job of uniquely identifying characters because those areas are simple, common outlets for expressing a character's uniqueness. Also, it's good tagging fundamentals to tag any features that are strongly represented in a given post, no matter how basic, like a focal character having mostly white, detailed_fur or an attention-grabbing horn. If something makes a post unique or stands out, that's a good tag candidate. What's more, if you're going to tag something basic like a horn or open mouth, you might as well go as far down the implication line as possible in the interest of time and specificity (e.g., white_horn also tags horn and open_smile also tags open_mouth).

darryus said:
tags have 3 general usages
browsing: using tags to just have a bunch of posts to look at
blacklisting: using tags to avoid seeing posts you don't want to see
searching: using tags to find a specific post based on elements contained within

Tag lists can also provide viewers with the names of things and help them interpret a post's content. I give those things high tagging priority and am willing to commit extra effort in tagging them correctly. Anecdotally, such tags may help a viewer figure out:

What's this fetish called? What type of hat is that? What the hell am I even looking at? What's happening bottom left? What's that emotion? Do the tagging overlords think this is consensual? Why is this rated explicit? I didn't see that they are streaming to Twitch! I missed the hidden camera. I didn't know that those are sex toys. Those tags make more sense than what I was thinking, and I can't see it any other way now. And so on.

I would be very interested in tag search analytics, meaning how often every tag is searched in aggregate. That would go a tremendous distance in identifying desired content (great for enterprising artists and uploaders), identifying higher priority tags for taggers, and revealing which tags may not be worth the tagging effort.

eeveesbeingassholes said:
Specific tags like: blue_body, white_scales, yellow_eyes, fangs, claws, horns. For example.
Those always made me curious, do people actually use them when searching? xD

Yep!

A couple years ago, I remembered a picture of a scalie (probably a dragon?) rimming a deer. I couldn't have sworn whether it was a dragon or some other kind of scalie, but I remembered he had an orange body.

The search string orange_body scalie deer rimming brings up a mere seven results, making it quite easy to identify the image I wanted to find (post #305477).