Need this especially on Jira Work Management forms where non-technical users need to provide technical information 

I would use this. 

This would be a great feature from various aspects of company and product workflows. Description text, and default text can only get you so far. The fields available to cover quite a bit, however without the capability to arrange (not just order and sort) the fields reduces effectiveness and further creates a desire for placeholder text in a textarea (or other) fields.

Another way of approaching this issue is to allow keyword text in a field such that, when a user clicks that string, or uses the tab key, the entire string is highlighted so when the user begins to type, the 'placeholder' string is replaced with what the user is typing.

An application like BBEdit has this feature where a string can be tabbed to in a document. eg: <# this is a valid tab target #>

Here is a simple, yet more ubiquitous use case for an entity wishing to collect info from a general source (usually less familiar with the process, or forms used)

Example 1:
As a <#USER#> I would like to <#PERFORM AN ACTION#> to <#PRODUCE RESULT#>

There are three ways, at least, to approach this problem. One that I have not come across yet is to allow Jira to save an entire result along with variable text inputs as the value.

Example 2:

As a <input type="text" value="USER" class=""> <br>
I would like to <input type="text" value="PERFORM AN ACTION"> <br>
to <input type="text" value="PRODUCE RESULT"> 

Whatever form this may take, having the ability to creat prompts or placeholders could make many departments able to better gather information, saving time and frustration.

I was just looking for a way to do this on our Jira Cloud instance. We'd like to be able to supply default text (for us, for the summary fields) so that for each issue type, the reporter will be reminded of our preferred naming convention for the type.

We'd also like to have separate default summary text for each different issue types so that we can have bugs summarized one way while stories are summarized a different way and reporters are reminded of the difference.

Yes please! As others mention, this is a key component in helping users stick with best practices.

Key requirement: placeholder text (unlike default values) do NOT count as a valid entry when the field is required. This is why default value is not a workaround for this.

This feature would be really helpful to guide users following organization best practices.

 news about this feature? We really need it.

Really needed feature for Text fields.

This is an important feature.

To help reduce too much variation in description format, see attached example of what I would like to do on a per project and per issue type basis.