For those of us who have been in this ecosystem for a couple of years (before tribes and communities), using the proper tags was very important so that our content was easier to discover.
Nowadays, generalized interfaces like PeakD and hive.blog switched to main views based on communities. On Ecency, one can still find the former topical-based organization, separate from communities (as far as I could see at first glance):
All tribe interfaces have some sort of support for tags related to their domain.
On Leofinance they show up as a topbar:
On CTPTalk (and I believe any other outpost-based interface because I also checked Splintertalk and it's the same) it's also a topbar, but only after you click the Explore link:
I'm sure if you have another favorite tribe interface, you can find these topics somewhere.
What are these Topics?
Simply put, topic = tag. But as with anything in the crypto space, nothing is so simple. :)
Topics are something of interest to us, like: hive, crypto, gaming, investments, online marketing, etc.
And it's a way to find the content and authors you might be interested in.
Let's say you want to find content about "defi" on Leofinance. You scroll until you find "defi" on the topbar, and click on it. You'll obtain something like this:
You can choose to filter posts tagged with "defi" based on the classic options: trending, hot, recent, and promoted (maybe these options need some upgrading).
Understanding Tags
When you publish posts on Hive, you can't do it before you add at least one tag, which is called the primary tag.
Most people publish their posts within communities nowadays. When you post in a community, the primary tag is set automatically to the community id. That's something that starts with "hive-" and a series of digits. Each community has one, and they are all unique.
If you want to ask me why aren't the names of the communities used instead, to make these tags human-readable, it has to do with the way things were designed initially to make sense for the communities from the coding point of view (community ids/tags are unique, community names not necessarily).
If you post using Leofinance, for example, you post both in the Leofinance community and in the Leofinance tribe.
What's the difference between them? Communities are a Hive thing. Tribes (or more recently, outposts) are a Hive-Engine thing.
Indexed and Non-Indexed Tags
Other than the first tag which is the primary tag (and which cannot be edited or removed after posting), a post most often has a number of additional tags.
Tags on Hive can be relevant to the topics discussed OR they may serve an additional technical purpose (much like the community id tag, but for additional purposes). In the latter category, we have the tribe tags.
The order of the tags matter!
That's because the first 5 tags are automatically indexed by Hive. These are the tags you can later use to search by and which help categorize your post.
Any tag following the first 5 tags is not indexed by Hive, meaning you won't find an article by searching by its 7th tag. If you want a tag to searchable, place it among the first 5 tags.
Remember! The primary tag is reserved for community tag, so if you post in a community you have only 4 tags left to be indexed.
Non-indexed tags are where you want to place your tribe tags, generally. That's because you don't need to index by that keyword, but want to have your post in that tribe or to receive that type of reward.
The total number of tags depends on the interface you use, most important of them settling at around 10, as far as I know. Using much more tags than that won't do you any service, as you might be accused of tag abuse.
You don't need to index a post published by Leofinance with "leofinance", for example (again, indexing = first 5 tags, including community tag). That's because your content will appear on the Leofinance interface. On all other interfaces, it can be found in the Leofinance community.
That's why the Leofinance interface auto-adds its "leofinance" tag at the end if you haven't added it before. I wonder if other interfaces still prefer to add it in front, as was the practice before tribes came into being.
What is Tag Abuse?
Generally, by tag abuse, we understand using unsuitable tags for your post on purpose to spam it into a community or on a popular topic. For example, using the "leofinance" tag for a post that has a picture of a dog/cat, insta-style. That's tag abuse.
Also using too many tags, and often all of them tribe tags can be considered tag abuse.
Why search for topics when we have communities? Isn't that enough?
I just gave you an example earlier in the post where topics make sense at the level of a community.
Leofinance has grown large enough to have content in different categories. I gave an example up there with "defi" and how you can find only posts with the "defi" tag on Leofinance.
The same can be done in other big communities and on Hive as a whole. So yeah, topical search can still be meaningful to discover content you are interested in on your favorite platform.