"We also collect (or rely on others, including Microsoft, who collect) information about your device where you have not engaged with our Services (e.g., ad ID, IP address, operating system and browser information) so we can provide our Members with relevant ads and better understand their effectiveness. We receive information about your visits and interaction with services provided by others when you log-in with LinkedIn or visit others' services that include some of our plugins or our ads, cookies or similar technologies."
LinkedIn tracks users across its own services, Microsoft properties, and third-party websites via cookies, pixels, ad tags, and device identifiers—even on sites where users haven't directly engaged with LinkedIn.