Explain the differences between first-party and third-party cookies and what options you have in a server-side GTM environment to utilize them.

First-party cookies are set by the domain the user is currently visiting (e.g., yourwebsite.com). They are generally used for things like remembering login information, language preferences, and items in a shopping cart. Third-party cookies are set by a domain different from the one the user is visiting (e.g., adnetwork.com). They are typically used for cross-site tracking, advertising, and retargeting. Browsers are increasingly blocking or restricting third-party cookies due to privacy concerns. In a server-side Google Tag Manager (GTM) environment, you have more control over how cookies are set and used. You can set both first-party and third-party cookies, but you should prioritize first-party cookies for enhanced privacy and data control. To utilize first-party cookies, you can use the 'Set-Cookie' HTTP response header in your server-side code. When a user visits your website, your server can set a first-party cookie by including the 'Set-Cookie' header in the HTTP response. This allows you to store data about the user on your own domain. In server-side GTM, you can read and modify first-party cookies using JavaScript code within custom templates or custom functions. You can use the 'document.cookie' property to access and manipulate first-party cookies. For third-party cookies, you can use server-side GTM to proxy requests to third-party vendors. When a user interacts with your website, your server can send data to the third-party vendor on behalf of the user. This allows you to control what data is sent to the vendor and to set third-party cookies from your server. However, due to increasing privacy restrictions, it is recommended to avoid relying on third-party cookies whenever possible. Instead, focus on using first-party cookies and other privacy-friendly tracking methods, such as cookieless tracking or aggregated data. By using server-side GTM, you can also implement consent management features that allow users to control whether cookies are set. If a user declines consent for certain types of tracking, you can prevent cookies from being set or modify their behavior. This helps to comply with privacy regulations and respect user preferences.