Testing using WordPress 5.7. Twenty Twenty One. Downloaded a special Gutenberg plugin containing this PR build.

This is really nice, George! Thank you!

Before:

After:

Frontend:

This PR also tackles this issue:
Saving tags before post creates unused/unwanted tags
#15406

I will add some issues that would be good to go through before this PR is merged.

Bug where tags disappear when adding tags in the create post view
#29077

#21589 (comment)
Associated issue: #22048

Tags and FormTokenField disappear when user don't add comma or click Enter Key
#16788
Associated PR: #16849

Suggested tags should be a list
#15291

#13282

To create a clearer distinguish between tags. You can add size differences based on how much each tag is used.
Here is a conversation about that: #8867 (comment)

It is similar to how it looks using the Classic Editor.

Btw
I added the above comment with issues. To see if there is anything there that could support this PR. If it is natural to add features based on those issues to this PR. Then go ahead and add it. If not then focus on the primary tasks, and the above issues could always be followed up in another PR (if need be). What is important here is the general improvement to tags.

Updated design to match Classic Editor.

Same design but without border:

I am wondering if we should stick to the Classic Editor framing the tags.
As it shows a very clear distinction of what is a tag and what is outside the tags area.

It looks like this PR is ready for a code review.
Thank you George for working on the tags feature! It will be very helpful to have the feature included in the Block Editor!

Going through this PR and to my untrained eye, this looks pretty nice. I do have a UX question, though: Should the "Choose from the most used Tags" button be visible when there are no terms available? Now it is, and I can imagine it can be confusing, because when no terms are available, nothing happens after clicking on the button.

We could add a fallback in the form of "You don't have any terms yet, click here to add your first", but that might be a bit redundant, because of the big fat "Add new term" form :) I'd go for hiding the button until there is at least one term to pick.

Thank you for the PR! This will be a good one to close, wow.

Here's before:

Here's after:

The specific interaction:

The feature is very useful, however the tag cloud as a concept has not scaled well:

• It makes oft-used tags easier to click and rarely used tags harder to click, as opposed to just rank them
• It adds visual noise with the size discrepancy that isn't great for accessibility with regards to people on the autistic spectrum or dyslexics.
• By scaling down less used tags, it can make them such low font size as to be hard to read.

The best aspect of the tag cloud is just a ranked list, which seems the simplest possible thing to do. Even something entirely basic like this would be better:

If you rebase this PR, the is-link colors should correctly pick up your admin theme color.

20 also feels like a LOT of suggestions. Can we do with less? 6? 8? 12?

@jasmussen Joen here is a link to a discussion on why it is nice to show the tags visually in different sizes:
#8867 (comment)

Some of the discussion has to do with having similar named tags. Having a visual difference makes it easier for users to select the correct tags.

Brainstorming...
It would be helpful to have a minimum font size for the tags, and then perhaps have some "break points".
Baseline for tags at 14 px (?).
Tags used between 3-5 times the font size changes from 14px to 16px (?).
Tag is used between 6-8 times the font size changes from 16px to 18px (?).
Tags is used between 9 - 11 times the font size changes from 18px to 20px (?).

I am at present not able to download the special version of the Gutenberg plugin. Option does not show up in the left sidebar in the Checks screen.

I respect that feedback, but my thoughts stand regardless. I don't see how the perceived benefit of relative sizing outweighs the accessibility downsides.

The "choose tags..." text, and the tags themselves both appearing as links is confusing, imo. @jasmussen's suggestion looks much better to me:

Instead of using font-size to rank the tags, could we just display them in descending order of use? If that's not adequate, each tag could have a suffix that declares it's number of uses:

Most used
First tag (12), Another tag (9), Third tag (5), Last tag (1)

Personally, I have a very hard time telling when terms start and end in the flat format example (probably closest to the "don't create a wall of text" note on the link @jasmussen posted).

I like that displaying count (like @jameskoster suggests) would make it clear that they're being ordered by most used, along with providing a delimiter between terms.

I wonder if on large sites if that might lead to it looking a bit off due to the length of the number, but I suppose it'd have to be 1000+ posts before it is 4 digits.

I should've also clarified that if we were to show just a plain list of tags, they should be sorted in order of usage just like Jay suggested, though I like the addition of the number count.

I wonder if on large sites if that might lead to it looking a bit off due to the length of the number, but I suppose it'd have to be 1000+ posts before it is 4 digits.

The tag plus number should probably be its own inline block so you don't accidentally get the number wrapping onto a new line without the preceeding tagname.

it'd have to be 1000+ posts before it is 4 digits.

At this point we perhaps we can do something like "2.3k".

Please check this comment in the issue:
#8867 (comment)

(It shows various mockups.)

Another suggestion could be to go with what George originally suggested and add a border/frame around the tags.
Something like this:

Then when a user hovers over a tag one will see a tooltip with the name and number of times it is used.

Tag: Example
Tooltip: Example (9)

A user will also notice that the tags are listed by what is most popular. The reason for not adding the (number) after each tag openly is that it creates visual noise. Word (number), word (number).

A lot of the discussion here is already done in the issue. With a lot of feedback from different people. So it is gone a few rounds already. I do hope to land the Tags feature this time.

Pushed another design updated as suggest by @jasmussen #30598 (comment).

The tag cloud is now ranked list that displays the 10 most used terms. The label - "Most Used" comes from the taxonomy object, and this is why it doesn't match the design 100%.

Misc changes:

• Component now lives in a separated file.
• I moved few utility methods into the utilts/terms.js file for convenience.

That looks much better, thank you @Mamaduka! This seems definitely shippable.

Question: does the interface show up always, even if you have zero or less than 10 tags total? If yes, should we limit it to showing up only when you have more than n tags, say 10?

Thanks, @jasmussen.

Question: does the interface show up always, even if you have zero or less than 10 tags total? If yes, should we limit it to showing up only when you have more than n tags, say 10?

I think it makes sense only to display this component if a site has ten or more tags. I will update the logic.

I've updated the display logic.

I am seeing this:

I miss having the "Choose from most used tags" text link which earlier opened up to show various tags.
Now it opens up directly to show the tags.
I see it this way:
Step 1.
User clicks to add a new tag or begins to type inside the text field box. (Does not care to see the most used tags.)
Step 2.
User wants to see the most used tags and clicks the text link to open up to see 10-15-20 etc tags.

The Tags feature has gone so many rounds. Let's just land and merge what we got. Things can be iterated upon if/when needed. Thanks for working on this feature George!

Thanks, everyone, for testing, reviews, and suggestions ❤️

I'm going to merge the current iteration later today.

I am just not getting it. Please enlighten me..:)

I installed and activated Gutenberg plugin 10.6.0 on a local test site.
Went to a All Posts screen. Clicked quick edit on a bunch of posts and added in 3 tags. The same 3 tags on 7 posts. I expected that going to any post and opening the Tags panel that I would see the Most used tags listing the 3 tags I used the most, but that did not happen.

Btw
I also logged into Make WordPress. (I am not sure if Make WordPress sites use the newest Gutenberg plugin.)

But I expected to see the top used tags. Independent of how many there are.

EDIT:
It is a lot easier to remember to add the correct tags when one sees these in a Most used list.
A close example from creating a Core Editor Agenda and Core Editor summary. Having the most used tags seen makes it a lot easier to remember to add the correct tags.