Explanation
When you enable URL Filtering, all web traffic is compared against the URL Filtering database, PAN-DB, which contains millions of URLs that have been grouped into about 65 categories.

Explanation
"The WildFire cloud-based malware analysis environment is a cyber threat prevention service that identifies unknown malware, zero-day exploits, and advanced persistent threats (APTs) through static and dynamic analysis in a scalable, virtual environment. WildFire automatically disseminates updated protections in near-real time to immediately prevent threats from spreading; this occurs without manual intervention"

Explanation
A knowledge-based system uses a database of known vulnerabilities and attack profiles to identify intrusion attempts. These types of systems have lower false-alarm rates than behavior-based systems but must be continually updated with new attack signatures to be effective.
A behavior-based system uses a baseline of normal network activity to identify unusual patterns or levels of network activity that may be indicative of an intrusion attempt.
These types of systems are more adaptive than knowledge-based systems and therefore may be more effective in detecting previously unknown vulnerabilities and attacks, but they have a much higher false-positive rate than knowledge-based systems.