The level 1 sites can be seen as your global site, your data scope in general, whereas level 2 sites are defined as properties that can be selected from the dataset. You can think of this as a filter for specific pages or categories that you have defined, and which will allow you to organize, classify and display predefined data more easily.
It is also important to know that for each site level, there are a maximum of 3 page levels, to enable you to cut out the desired data perimeter and make better use of the Piano Analytics tool.
Here is a little illustration to help you understand:
Level 1 site (your site in general)
⤷ Level 2 site (defined perimeter of data)
⤷ Page - 1st level
⤷ Page - 2nd level
⤷ Page - 3rd level
To implement level 2 sites, here is an example of code you can implement to collect level 2 site information:
pa.sendEvent('page.display', {
'page': 'My page'
'site_level2': 'sub level' ,
'article_date': 1646925124,
'article_premium': false
});
If necessary, you can consult this documentation which details how to send events: click here.
The data will then be sent to the "Level 2 sites" property (level2_sites) in the interface.