Once upon a time, getting rid of unflattering or compromising photos was as simple as burning the negative.

We've all seen enough embarrassing videos on YouTube and websites devoted to cringe-worthy family portraits to know those days are gone - helped along enormously by the convenience, speed and permanence of digital technology.

We're all guilty of passing on irresistibly awful Internet photos and videos to our friends - usually of people we've never met. But the last thing we want is to see ourselves - or our children - unexpectedly pop up onscreen one day.

Before you upload a picture to the Internet, your phone or email, ask yourself: Would you be comfortable with your grandmother seeing this? What about your boss? If the answer is no, then don't post it online. It's good advice for your kids too.

Once an image is 'out there', it's difficult, if not impossible to control where it goes.

While digital technology has made taking and uploading photos so much easier, it's also made cross-checking even more important.

If you take holiday snaps of your children and their friends on the Christmas break, it's only reasonable to ask their parents if you can upload the photos to your Flickr site.

In most cases, there will be no problem. But there may be issues of which you are unaware, that could make an innocent photo uploaded to the web a source of future trouble.

Gary Poulton teaches visual art, photography and design at Wyndham College. He says there are lots of reasons parents might not want their child's photo on the Internet for all to see, and schools have to have written parental permission to photograph children.

"It's to protect the identity of children and especially those who may be involved in a custody dispute or other legal case," he said.

If you're photographing the school play, swimming carnival or social dance, it's wise to check with parents before making those pictures widely available. Many parents create Internet groups that allow them to share information and pics amongst registered users only - for example their classmates.

What are the legalities of posting photos online or even just taking photos of people in a street scene?

The Australian Privacy Foundation says that it's a complex area and there's no law in Australia specifically against taking a person's photo, with or without their consent (for non-commercial uses). The rule of thumb should always be to consider ethics and courtesy.   

Ian McDonald, a lawyer with the Australian Copyright Council said that some venues restrict the taking of photos (sporting and concert venues, art galleries and theatres), while some councils may have policies or bylaws in place with regard to taking photos in particular locations such as on beaches or at swimming pools.

If you're taking photos for commercial purposes, there are even more considerations.

"There are also laws relating to the taking of commercial photos in places such as the areas controlled by the Sydney Harbour Foreshore Authority," he said.

In most cases, if you take a photo, you are automatically the copyright owner.

But, once you post it to a photo sharing forum such as Flickr or PhotoBucket, the usage rights of your image may be transferred to the service provider (in the case of Flickr, to Yahoo!7) and possibly on to third parties. In short, you still own it, but any number of people can use it however they want.

When you're uploading photos or videos to sites like these, you're often given privacy options which allow you to limit access to your photos to pre-registered friends only.

Think about the photos you have of your home, your child's soccer team, your family holidays. Do you really want strangers to have that much information about your family?

Read the fine print. If in doubt, opt to allow limited access to your images, to known contacts in your address book only.

In websites such as Flickr and Facebook, this is usually done by altering your profile information - usually through a drop down menu or tick box under the Profile, Account or Settings section link on your homepage.

If you decide to remove material you have posted to your own website or blog, you can remove it quickly and easily.

However, images you have contributed to someone else's website - such as a moderated forum, or a public sharing website - will require you to ask the administrator in writing to remove it.

As websites such as Flickr can have legal rights to use your photos, you should write to the administrators telling them that you are removing this image, especially if there is the threat of legal action.

They are then obliged to halt any further distribution of this image. Bear in mind search engines like Google may hold a cached or duplicate version for several days after your image comes off the site. (Which means it may still be available for viewing.)