Creating a widget (displaying an advertisement)?

Question

Web development

I understand Laravel. The task is this: There are two types of accounts on the site: webmasters and advertisers. Advertisers add advertising campaigns (text+image), and webmasters add their sites. After creating an advertising company, advertisers can choose the platform (website) on which the advertisement will be displayed.
All this functionality is already there, it remains to create a widget that will be installed on the webmaster's website, which will display ads. I have never encountered this, I ask for advice, in which direction to dig?
As I thought - the widget must access the php script with a specific key, this key will be used to display an advertisement for display on the site.
I am doing the project purely for the purpose of learning laravel, so you should not take these functions seriously.
PS. In addition to all this, I still want to somehow register clicks on the ad

Answer 1

The identifier of the site / placement for which the ad block will be generated should be transmitted. Relying on http referer and other parameters is not worth it in this case. Of course, you can check and write them down.
Now even websocket is used to bypass blockers.
Usually there is a JS layer in which the ad unit ID parameter is passed. This parameter is already further sent when requesting advertising from the server.