A network sniffer is a tool used to monitor and analyze data packets traveling over a computer network. It captures this data to help network administrators troubleshoot issues, optimize performance, and ensure security. By examining the information in these packets, they can identify problems like slow connections or unauthorized access. These tools can be both hardware and software-based. Common examples include Wireshark and tcpdump. While network sniffers are essential for legitimate network management, they can also be misused for malicious purposes, such as intercepting sensitive information, making security measures crucial for protecting data integrity.