Type-in traffic is "natural" and direct traffic resulting from users entering directly a domain name, including the extenson, in a browser address bar. Type-in traffic is one of different kinds of direct traffic reported in web analytics data.
Type-in traffic can be due to domain or company notoriety, to typos, or to web users trying their luck by entering a generic term with an extension - shoes.com for instance. The last two forms off type-in traffic are almost the only source of traffic and revenue for parked domains.
Type-in traffic has been dwindling for many years and is still decreasing as users are more and more inclined to type domain names in search engine’s search boxes rather than in the address bar.
That tendancy has little effect on "traditional" websites but has serious implications for domain parking.