Children under 13 can do less on the Internet these days in part because of a federal law designed to protect their privacy.

In the past year, kids site Zeeks.com closed its chat rooms and disabled e-mail accounts for children. Internet matchmaker eCrush dropped users under 13, as did America Online’s ICQ service. Alloy Online banned young children from contests. Children under 13 can do less on the Internet these days in part because of a federal law designed to protect their privacy. The law, which marks its first anniversary a week from Saturday, requires sites that attract children under 13 to get permission from parents before asking for names, physical locations and other details that could expose kids to marketers and molesters. Scores of sites have re-evaluated whether they really need all the information they had previously collected, and many have improved mechanisms to get parental consent. But others simply dropped services or limited usage to avoid paperwork. Zeeks.com tried keeping its services for a few months, but ultimately decided that staffing, equipment and storage of consent records would cost $200,000 a year. Traffic dropped by 20 percent when Zeeks took away chat rooms and e-mail accounts, said Steve Bryan, the company’s chief executive. The company couldn’t make money and sold the site a few weeks ago. Under the law, sites could still collect those details, but they need consent. Chat rooms and other interactive features are covered because kids may let such details slip. The law covers only information collection, not content restriction. The law affects sites that target or know they have young kids who live in the United States. Violators are subject to fines of up to $11,000.