You have a website and want to start gathering and reporting insights for it in Google Analytics. What should you set up first?

Analysis of Correct Answer(s) - The Analytics tag (also known as the Google tag or gtag.js) is the correct answer. This is a snippet of JavaScript code that must be implemented on every page of a website to begin data collection. - Its core function is to send information about user interactions, such as pageviews, events, and transactions, from your website to your Google Analytics property. This tag is the foundational requirement for gathering any website data.

Analysis of Incorrect Options - Google Ads: This is Google's advertising platform. While you can link it to Google Analytics to import campaign data, you must first have the Analytics tag installed on your site to collect the underlying user behavior data. - Firebase SDK and Analytics SDK: These Software Development Kits (SDKs) are the correct implementation for tracking user activity within mobile applications (iOS and Android). The question specifically asks about a website, for which a JavaScript tag is the standard method, not an SDK.