When I take a photo with, say, my iPhone, it carries certain data including where and when it was taken, as well as the sort of device it was taken on.

Does that information stick with the photo if it gets circulated around the internet? So, for example, were I to photograph my bike, upload it to a blog, then link to it here in the forum, and one of you were to love it so much you downloaded it to your desktop… Would that photo, now that it is on your desktop, still carry the information above?

depends where you upload it

I believe Facebook automatically deletes it from the file, for example

EXIF info should be stripped out by the software doing the uploading. facebook, twitter etc do.

What about wordpress, blogger, and tumblr?

Depends on the site, I’d have thought. A social media site like Facebook would be more likely to strip EXIF data (which is what the data you’re referring to is called) than a dedicated photo hosting site (I’m reasonably sure Flickr doesn’t unless it’s changed since I last looked).

“Yes”. And also “depends”.

The info you are talking about is called EXIF metadata

Some photo hosting places will deliberately strip it out for privacy reasons.

Other places go the other way and make it more public – providing info tabs that detail the location, camera etc

There are lots of programs out there that will strip the EXIF data for you if it is a concern.
https://www.howtogeek.com/203592/what-is-exif-data-and-how-to-remove-it/

What Is EXIF Data? 3 Ways to Remove Metadata From Photos

With photo sites, like Flickr, you can control how much EXIF others can see….

On Flicker you have to set this in the settings.

Photography specific sites (Flickr etc) will retain EXIF data as people like to know the camera settings that were used, though I think you can hide them / strip them as an option. [Edit: beaten]

I’m not sure how many you can explore data such as GPS cords on though if that’s what you are worried about?

Facebook strip the EXIF before they display it, but they do store it, and they do use it. It’s how they tag your photo with the location it was taken, for example.

No social media business will give up info it could later use for money making.

Exactly – if you’d rather they didn’t have it then strip it before you upload it – don’t rely on them doing it for you.

Just disable the option on your iPhone.

Could do, but that messes up the ability to automatically organise your photos for your own use.

I use Lightroom to organise my photos, I can add tags to my heart’s content. When uploading I’ll use the “Save for Web” option and check the “remove metadata” box. See this for how

No social media business will give up info it could later use for money making.

You mean to pay for the service you get for free…