In a blockbuster security move, Google is spending $5.4 billion to acquire threat intelligence and cybersecurity services superstar Mandiant in a move to take Google Cloud’s security business to the next level.

“Together we can make a profound impact in securing the cloud, accelerating the adoption of cloud computing, and ultimately make the world safer,” said Google Cloud CEO Thomas Kurian in a statement Tuesday.

Mandiant is set to become part of Google Cloud this year as the companies unveiled plans for Google Cloud to buy Mandiant for $23 per share in an all-cash transaction valued at $5.4 billion.

It is key to note that this marks the second largest acquisition in Google’s 23-year history, trailing only the search giant’s $12.5 billion purchase of Motorola Mobility a decade ago in 2012. Google Cloud’s acquisition of Mandiant is subject to Mandiant stockholder and regulatory approvals and is expected to close later this year.

From Microsoft recently bowing out of its reported interest in buying Mandiant to Google Cloud’s technology synergy plans for the security all-star, CRN breaks down five of the most important things you need to know about Google Cloud’s planned acquisition of Mandiant.