Using a computer to dial telephone numbers within a given range, usually with the intention of finding a modem carrier signal. The practice largely predated the widespread penetration of broadband Internet connectivity; at the time, many businesses, agencies, and individuals operated computer systems "on-demand" through telephone-based modems, each of which might (or might not) offer a unique (and possibly privileged) selection of information, as well as possibly offering access to powerful hardware or a platform for reaching other networks and systems. Usually, the wardialer would be covertly planted on a public, shared, or corporate phone line, left to operate for a limited time, then retrieved so that any "positives" (phone lines returning a modem carrier signal) could be investigated later from yet another location. The practice often went hand-in-hand with phreaking, for obvious reasons.

Today, some telemarketing and social research firms use similar programs (usually working from a digital phone book) to reach residential numbers in search of sales or social information. Also, on rare occasions, people engaged in social engineering have used a form of this process to explore "gaps" in corporate phone listings to discover (and identify the owners of) unlisted numbers.

This term directly inspired...

When you don't use your real name on myspace, in turn making it impossible to find someone using the search function.

Reverse lookup sites track unlisted and unregistered numbers

The vocal sound to describe a act of dumb, or a view/image of dumb, seen as a meme, and used on image boards(websites unlisted for certain reasons).

there's your one defination

One who deletes the end of a file name to look at the unprotected parent directory or index of a webpage.

Svedish vord for Vorld, as pronounced, or in English, world.