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Your Privacy and online searching: Are you being compromised

Privacy fact sheet

Online Behavioural Advertising: Know your options

Companies use online behavioural advertising (OBA), also known asinterested-based advertising, to try to match the ads you see while browsingonline with your interests. Advertising and data collection companies do this byplacing a cookie on your computer (cookies are explained below).

Interest categories, based on the sites you visit, are attached to thesecookies and can allow advertisers to build up a picture of your browsing habitsand interests. These interest categories can then be used to deliver ads. Somepeople don’t mind receiving ads that are targeted to their interests but it’sstill important to be aware of how information about your browsing habits andinterests is being collected and what your choices are.

The Privacy Act applies to ‘personal information’.  Personal information isdefined in the Privacy Act, but broadly speaking, it is information that can beused to identify you. The information collected by online advertisers may oftennot be sufficient to identify you; it might just be general information aboutyour interests and sites you have visited. So companies using OBA may not needto comply with the rules in the Privacy Act about how personal information ishandled.

However, it is important to remember that new technologies make itincreasingly easy for the pieces of information that you provide when you areonline to be combined. This process, called data aggregation, can provide a muchclearer picture of who you are.

Did you know?

Many ads on websites are not placed there by the web site that you visit,they are provided by advertising networks which act as brokers, connecting websites that want to sell advertising space with advertisers that want to reachpotential customers. The same advertising network may deliver ads to manywebsites and may be able to track your browsing activities across many sites.The website you visit may also have its own analytics tools and trackers runningto collect information such as the numbers of visitors to the site, how longthey stay, and how they navigated to the site.

Know your browser

Different browsers have different settings and features that you can use tohelp control your personal information online. It’s worth checking out theseoptions and comparing what different browsers offer, to decide what’s right foryou. Common options include deciding whether to accept cookies and how long toallow them to stay on your machine. Some browsers also have additional privacyfeatures that you can download and install.

Did you know?

Many browsers offer the option of browsing in ‘private mode’. This usuallymeans that while this setting is active, your browsing and download historywon’t be saved to your computer. It doesn’t mean that the browser willautomatically block all tracking of your activities online.


A cookie is a small text file stored on your computer’s browser. Many cookiesfrom websites will be visible from your browser. You will usually findinformation on cookies and how to manage them under ‘options’ or ‘settings’ inyour browser. You can choose to see cookies before deleting them and to keepcookies from some sites.

There are several different types of cookies.  A ‘first party’ cookie is sentfrom a web site to your web browser when you visit that site. This is howwebsites ‘remember’ things like your customised settings (eg your location),your shopping cart contents and your log in details.

Temporary cookies only last for one browsing session (until you close yourbrowser), while persistent cookies remain on your computer after you close yourbrowser and will be sent back to the web site each time you visit.

Third party cookies are sent by businesses that provide content, likeadvertising, on web sites that you visit. Many web sites feature advertisingfrom third parties and those third parties may use cookies to track yourbrowsing activities. As explained above, advertising and data collectioncompanies can use this information to deliver advertising that they think maymatch your interests – this is online behavioural advertising.

Another type of cookie is the Local Stored Object (LSO), also known as aFlash cookie. These can contain more information than a regular cookie and arenot generally cleared when you clear cookies from your browser. Depending onyour browser, you may be able to install a plugin that will let you block ordelete LSOs. You can also manage these cookies via the settings page in AdobeFlash.

Did you know?

Setting your browser to block all cookies may make some web sites take longerto load and stop you saving customised settings such as text sizes, location orlogin information. You can use the settings in your browser to control  how youdeal with cookies, for example, you can choose to allow all first party cookies,to allow all first party temporary (session) cookies, to be asked whether youwant to accept each cookie, or to block all third party cookies.

Opting out

Some companies that deliver OBA give users the options of viewing theirprofile, editing it or opting out of receiving targeted ads. Sites that let youcontrol what information is collected about you include Your Online Choices, Evidon Privacy Choice and Google’s Ads Preferences Manager. Whenyou opt out of receiving targeted ads, this information is usually saved on acookie. This often means that if you clear your cookies, you’ll have to opt outagain. Some browsers are beginning to offer opt-out tools that won’t be affectedif you clear your cookies.

Did you know?

Opting out of receiving targeted ads doesn’t always mean that informationabout your browsing habits won’t still be collected. For example, some optionsrely on advertisers signing up to an agreement not to collect information aboutbrowsing activities if people ask not to be tracked online. This will not affectadvertisers who do not choose to be part of that agreement. There are othertools available, such as Ghostery  and Tracker Block , that will help you see which trackers are active on pages that youvisit and allow you to block them. Note that these tools will work differentlydepending on your browser.

The information provided in this fact sheet is of a general nature.It is not a substitute for legal advice.

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