Pixel based tracking is the process of using a 1X1 pixel transparent gif to track a visit or event on a webpage, to track ad impressions or to track opening for an email. On webpages, pixel tracking is an alternative to javascrip tracking.
Pixel tracking is used for many occasions in digital marketing context:
event tracking on webpage for analytics
conversion tracking by marketing vendors and affiliate platforms
for cookie pooling in retargeting
for opening measurement in email campaign
An HTML code snippet including the pixel request is provided by the third party that want to track user behavior and placed on webpages. For email campaigns, the snippet code is automatically add within messages by the email service provider. For ad tracking it is tied to the creative code.
When the page is visited or the event occurs, an image request is made by the user’s browser to the server in charge of tracking. Different parameters are passed within the HTTP request to the server to qualify the action. Then the server sends a clear gif image and most often a cookie is dropped.
An example of code snippet with parameters used for Yahoo analytics:
An example of HTTP request completed according to the registered action:
Cache busting techniques are also used with pixel tracking.
In email marketing, pixel tracking can’t track opening when images are blocked or the device not connected to the Internet.