Final answer:
A firewall is the tool that filters inbound traffic to diminish potential threats, acting as a barrier between a computer/network and the Internet, based on defined security rules.
Step-by-step explanation:
A tool that filters inbound traffic to reduce potential threats is known as a firewall. Firewalls serve as a barrier between your computer/network and the Internet, monitoring incoming (and often outgoing) traffic based on a set of defined rules. They are designed to prevent unauthorized access while allowing legitimate communication to pass through.
While antivirus software protects against malware, intrusion detection systems (IDS) monitor network traffic for suspicious activity, and encryption tools safeguard data by converting it into a coded format, it is the firewall that is specifically responsible for filtering inbound traffic.