Internet-based measurement is a set of methods applied to quantitatively describe the structure, workload and use of the Internet. They provide a practical means of doing a kind of virtual ‘fieldwork’ on the Internet using online tools and network monitoring techniques to gather fine scale primary data. Internet-based measurement as a methodology for human geography is important because it (1) provides insight to the underlying structural processes of the Internet and Internet based activities; (2) allows users to explore and analyze the Internet for themselves; and (3) allows researchers to aggregate data spread across multiple websites to analyze offline phenomenon. After outlining the five distinct kinds of geographical locations associated with an Internet based resource (lexical, hardware, production, ownership and use) this chapter outlines a range of tools and techniques for exploring these geographies. These include IP address geo-coding, domain name whois lookups, website rankings, ping, and traceroute. These tools can provide an understanding of the topological structures and geographies of the Internet, and allows users to construct information first-hand and critically question network operations directly.