Spam refers to unsolicited bulk communications sent without recipient consent. Originally an email term, it now encompasses spam calls, SMS spam, and junk fax. The name derives from a Monty Python sketch where every menu item contains SPAM (canned meat).
Phone spam (spam calls) primarily uses auto-dialers to mass-call phone numbers, capable of tens of thousands of calls daily. Answered calls receive recorded messages or are connected to operators. In Japan, spam calls mainly involve telemarketing, investment fraud solicitation, and fictitious billing.
SMS spam (smishing) is equally serious. Fake delivery notifications and bank alerts are mass-sent to lure victims to phishing sites that steal personal information. SMS's approximately 98% open rate makes it highly efficient for attackers.
Countermeasures include carrier-provided call/SMS filtering services, call filtering apps, and habitually not answering unknown numbers. Japan's "Act on Regulation of Transmission of Specified Electronic Mail" regulates commercial mass messaging with fines up to 30 million yen. See how to block nuisance calls for practical tips.