Shopify
A universal pixel is a small snippet of code that should be installed in your theme.liquid file
How to Install the Pixel:
1) Login to your Shopify Account.
2) Navigate to your Sales Channels on
the left-hand side bar, then choose 'Online Store' and click on the 'Themes'
button.
3) Next click the 'Action' menu on the
right side of the screen and choose 'Edit Code' form the drop down menu.
4) Select 'theme.liquid' from the layout folder.
5) Scroll down to the bottom of the file and place your pixel just before the closing body tag.
6) Click 'Save' at the top of the screen to save the file. That's it.
Additional Scripts
1) In order to add the purchase event to the checkout confirmation page you'll need to navigate to Settings > Checkout
2) You'll need to find Additional Scripts in the Order processing section.
3) Place the conversion pixel in Additional Scripts and save.