I belong to several Facebook groups dedicated to copywriting. Every so often, the phrase, “find your niche” comes up. I’ve asked for a definition several times, and each time gotten a different answer. 
Does it mean the type of copywriting I excel in? 

Or,

Does it mean the subject areas that I specialize in?
I’ll start with a story about the second. I’ll skip the long beginning of how this came to be, but a marketing consultant got a bunch of writers together and assigned us each a subject area. Mine was chiropractors. He had me re-write my LinkedIn profile to focus on chiropractors. He used some voodoo software to invite hundreds of chiropractors to like my page. I got many responses, which were automatically replied to, but in the end, not a single chiropractor took me up on my offer.

Could it be that:

Chiropractors don’t see the value of marketing?

I was in the wrong niche? Or…

Niche doesn’t mean subject, but instead type of content.

I believe it's # 1: Niche means the type of copywriting I excel in.

No one has ever called me to ask, “do you specialize in chiropractors”? Instead I’m asked, 

“Have you ever written a newsletter, website, script, white paper, etc.

My latest three clients have completely different businesses, and each has wanted something different. And in all three cases, I’ve quickly learned their business so that I could deliver a great training site, article, and white paper. 

And if someone calls and askes, “Can you write a 10-page direct sales letter?” I’d have to say no. Not my niche. Long-form sales letters, that is.

After much consideration I’ve found my niche: Being a well-rounded copywriter.