Google's "Year in Search" campaign is an annual initiative that highlights the most significant events, trends, and moments that captured global attention over the course of the year based on Google search data. These campaigns typically include a video montage that features key search terms and themes, providing a retrospective of the year's most impactful and memorable events. Here's an explanation of the "Year in Search 2019" campaign:

1. Video Montage: At the center of the campaign is a video montage created by Google. This video features clips and images related to the most-searched topics and events of the year. It is designed to be emotionally resonant and often includes uplifting and inspirational moments alongside more somber and reflective ones.

2. Data-Driven Content: The "Year in Search" campaign is based on real user data collected from Google searches throughout the year. Google analyzes the search queries, trends, and patterns to identify the topics that dominated public interest and conversation.

3. Global Perspective: The campaign often highlights both global and regional trends, providing insight into what captured the attention of people around the world. It celebrates the diversity of interests and concerns across different regions and cultures.

4. Reflection on the Zeitgeist: The "Year in Search" campaign serves as a reflection of the cultural and societal zeitgeist of the year. It showcases the events, figures, and moments that defined that particular year, making it a time capsule of sorts.

5. Emotional Storytelling: These campaigns are known for their emotional storytelling. They often include personal stories and individual journeys that resonate with viewers. The goal is to connect on a human level and remind people of the power of search in capturing the essence of a year.

6. Promotion Across Platforms: Google promotes the "Year in Search" campaign across various platforms, including its own search engine, YouTube, and social media. The videos are typically widely shared and discussed, adding to their visibility.

7. Reflection on Societal Issues: In addition to celebrating positive moments, the campaign sometimes touches on significant societal issues and challenges that arose during the year, showing Google's awareness of its role in reflecting the world's concerns.

8. Impact and Engagement: "Year in Search" campaigns tend to engage a wide audience, from casual internet users to media outlets and influencers who comment on and share the video. They serve as a conversation starter and an opportunity for people to reminisce about the past year.

In summary, Google's "Year in Search" campaign is an annual retrospective initiative that uses real search data to provide a snapshot of the year's most significant moments and trends. It combines data-driven insights with emotional storytelling to create a compelling narrative that resonates with a global audience. These campaigns reflect Google's role as a curator of information and a mirror to the world's interests and concerns.