The Internet’s address system is about to undergo its largest expansion since it was first created in the 1980s—a change that will force companies to do more work and spend more money to protect their brands, lawyers say.

Many brand owners and organizations have already taken steps to protect themselves by formally objecting to some of the almost 2,000 new applied-for top-level domains (TLDs) that are under review by the Internet Corporation for Assigned Names and Numbers (ICANN), the nonprofit organization that coordinates domain names and is overseeing the expansion. TLDs are the string of characters to the right of the "dot," such as .com and .net; there are currently only 22 such domains.