First Party Cookies Are Cookies Enabled By & For The Website You’re Visiting
First Party Cookies are common instruments in helping to promote user experience through stored information. This is common when a website remembers things about a user from page to page, visit to visit, etc.
The question of “Party” in these is based on where information is stored. In order to be “1st Party” information must be stored on the domain it is gathered on.
The opposite of First Party Cookies would be Third Party Cookies.