When you take a cute selfie on holiday and post it to your 160 followers on Instagram, you're probably not expecting it to show up in a national news story read by hundreds of thousands.

This happened to some people who took a happy snap with wild wombats on Tasmania's Maria Island then posted their pictures using popular tourism hashtags.

Two of the users were so shocked their snaps appeared in an ABC story that they contacted the journalist threatening legal action, claiming their photos were private and using the pics was breaching copyright.

These people didn't know what their Instagram privacy settings were set to and weren't across what is and is not allowed when it comes to public posts on social media.

Jennifer Stokes is a lecturer in digital literacy and future ideas at the University of South Australia and she says it's pretty common for people be confused about the finer details of what's allowed with social media, even when they're very familiar with how to post.

"We have people who've grown up with the technology and we might think they're across it, but actually quite a few of the nuances aren't so visible," she says.

"I think a lot of people just use the technology in a perfunctory way."

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Who can see what I post?

Depending on your settings, that snap of dinner could end up just about anywhere when you post to social media. ( Unsplash: Igor Miske )

Let's start with the basics; Instagram has two options for your account — public, which is the default setting, and private.

Anything posted by a public account is visible to anyone looking at Instagram or anywhere else where the post might be cross posted (Instagram accounts can be set to post to Twitter and Facebook, for example).

If your account is public, anyone can follow or see your posts unless you block them. If you switch to a private account, followers must ask permission to follow you.

Anything posted by a private account will only be visible to those you've been approved as followers, even if you use a hashtag.

"If your account is set to private, and you include a hashtag or location geotag in a post, only your approved followers will see your post on the hashtag or location pages," Instagram Australia's Jeff McBride says.

"This includes photos you've been tagged in by other people — only confirmed followers can see photos and videos you're tagged in on your profile."

Ms Stokes says finding the settings on apps like Instagram can be a little tricky on the mobile phone, which can be why many users don't realise they even have the option to make something more private.

"There's more than 4 million Australians who access the internet solely through a mobile connection," she says.

"They might not even realise what their privacy settings are set to."

What are hashtags for anyway?

Hashtags are used a lot on Instagram and Twitter (and bit less on Facebook) as ways to makes your photos and tweets searchable.

"You can use them to search for posts and people who share your interests," Mr McBride says.

"For example, a plant lover might search for #urbanjungle to uncover a whole world of leafy content, or a wedding may have a fun hashtag so that the attendees can share their photos with each other."

If your account is public, that means anyone can find your post if they search the hashtags you include. This can be great if your aim is to make your photos more discoverable.

Location tags and tagging other users are other ways you can help people find your stuff, which, again, is great if that's what you want.

If you don't want strangers finding your stuff or knowing where you are when you're posting, you might not want to add all the tags.

Who can use my posts?

Agreeing to the terms of use of a social media platform such as Facebook or Instagram (which you must do to begin using them), means giving that platform permission to use anything you post in a variety of ways.

Jo Teng, a senior lawyer with the non-profit organisation Australian Copyright Council, says while you still maintain copyright of what you create, by using the platform you're agreeing to give them a licence to your stuff.

So when you sign up for Instagram, you give them a licence to host your content, publish it and show it through the Instagram framework and this includes allowing posts to be embedded. Like this, the world's most 'liked' Instagram post:

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That said, though, if your account is set to private, an embedded post won't work.

What about copyright?

Being in a photo does not give you any rights over that image. ( Unplash: Rawpixel )

Ms Teng says there a lot of common myths and misconceptions around copyright in Australia.

Copyright is designed to protect your rights to control what you create and applies to things that have been created, such as a song you've written, a poem or a computer program — but it doesn't apply to ideas, styles or a technique of doing something.

The creator of the work owns the copyright unless it was made as part of their employment or is commissioned and paid for by someone else for private or domestic use, this means a wedding photographer generally doesn't own copyright, the couple who hired and paid do.

Here are some of the basics of Australian copyright law:

It is free and automatic — there is no registration or fees for copyright in Australia

It is free and automatic — there is no registration or fees for copyright in Australia The copyright notice symbol — this one © — isn't needed but can be handy to make people aware that copyright exists on that work

The copyright notice symbol — this one © — isn't needed but can be handy to make people aware that copyright exists on that work There's no copyright on your face, so you don't own copyright of a picture you're in — if your friend takes a photo of you, then they own the copyright

There's no copyright on your face, so you don't own copyright of a picture you're in — if your friend takes a photo of you, then they own the copyright When you create an account with a social media platform, you have to agree to their terms of use. Writing your own disclaimer has no legal grounding if you're using the platform

When you create an account with a social media platform, you have to agree to their terms of use. Writing your own disclaimer has no legal grounding if you're using the platform Australian copyright law only applies to stuff created in Australia. Copyright law is similar across the world, but each country has its own approach and interpretations, so best to get advice for international matters.

How your photo can end up on the news

Media organisations are always looking for imagery for their stories — and they have certain rights to use your social media photos and videos. ( Unsplash: Ian Dooley )

The rise of social media has been a bit of a bane for traditional media outlets, as they compete against the global publishing giants for clicks and attention.

"We're [the public] so used to looking at social media as the first point for anything major," Johanna Baker-Dowdell, senior journalist at The Examiner, says.

"Traditional media like radio, newspapers or even TV would be the second option now."

Ms Baker-Dowdell is a PhD candidate at the University of Tasmania and has been researching how newsgathering and social media interact during crisis events.

"They're [media outlets] always looking for someone who can help them tell the story," she says.

"So that's someone who was there who can give them that first-hand account or someone who had taken photos or video."

Journalists scan social media looking for people they can speak to who might have posted proof they've seen something or know more about an event or topic. And they're also looking for photos or video they can use in their stories.

While it's best practice for the news outlet to ask for permission to use someone's photo, if the post is public, that might not always be the case.

News outlets can use some copyright material if they can justify its relevance to the story and that the use is "fair", which is known as fair dealing.

And if your account is public, anything you post can be embedded just about anywhere without you ever knowing.

"If it is embedded, the permission is implied because [the publisher] is showing where it's come from," Ms Baker-Dowdell says.

"Most social media platforms do have a disclaimer, that most people don't read, that content you post can be used for other purposes."

Do a regular 'vanity check'

Ms Stokes says while most of us are online in some form, less than half of us feel empowered by digital technology.

"It can be quite an intimidating space," she says.

Ms Stokes says she recommends people regularly check what their privacy settings are set to on all their social media accounts, as things can change.

"It's also worth doing things like a vanity check every six months or so, just googling yourself and seeing what comes up," she says.

Mr McBride recommends going to Instagram's Help Centre for more specific information on how to stop your images appearing in Google search results, who has the ability to comment on your images, and how you can have more say in who sees your selfies.

Editor's note: This story has been updated to include information about fair dealing in relation to the media's potential use of copyright images.