Packet sniffing is usually sniffs wireless transmissions. Sniffing is the interception of data or packets. The person who is suppose to receive the information still does but a third party has the ability to eavesdrop read the data. Packets can range from harmless info like your latest homework assignment or other more sensitive information like your Bank statement. The method to avoid a person sniffing your data sent wirelessly is to encrypt the data with modern day encryption algorithms.