What if you are faced with spam in Google Analytics reports? Does it mean that someone can access your Google Analytics accounts? Or maybe someone can modify data inside your GA? How can you prevent it? There are two main types of Measurement Protocol spam: referral traffic and events spam. More rarely you can see spam in languages, keywords, URLs, transactions, and so on. In this article, I will explain what Measurement Protocol spam is and how you can prevent it with the help of Google Tag Manager Server-Side tagging.