Which element is required to create a Custom Audience from website visitors?

To create a Custom Audience from website visitors, you need the Facebook Pixel. Here are the steps:

1. Install Facebook Pixel: This is a piece of code that you put on your website. It collects data that helps you track conversions from Facebook ads, optimize ads, build targeted audiences for future ads, and remarket to people who have already taken some kind of action on your website.

2. Set up events: Events are actions that happen on your website (like when someone makes a purchase). To set up events, you'll add more code to your Facebook pixel code.

3. Create a Custom Audience: Go to your Facebook Ads Manager, navigate to the Audiences section. Click on "Create Audience" and select "Custom Audience".

4. Select Website Traffic: You'll be given a few options for the type of Custom Audience you wish to create. Select "Website Traffic".

5. Define your audience: You can include all website visitors, or you can define your audience based on specific web pages they visited or actions they took.

6. Save your audience: Give your audience a name, save it, and you're done. Now you can use this audience for your Facebook ads.

Remember, you need to have enough website traffic to create a Custom Audience. Facebook requires a minimum number of visitors to be able to create an audience.