Spam exists in various forms of internet communication like email, instant messages, discussion boards and internet telephony. Email spam is the most common type and involves receiving unwanted advertisements and marketing emails. Spam grows as communication technologies evolve and spammers find new cheap ways to advertise. While spam can never be fully stopped, individuals can take steps like using strong passwords, email filters and antivirus software to reduce the amount of spam received. Other forms of spam include SPIM (spam over instant messages), SPIT (spam over internet telephony) and avoiding public exposure of contact details can help limit these.