Google, Yahoo, eBay and Microsoft, competitors on the Web, all have the same idea for marketing themselves this holiday season: temporarily providing free Wi-Fi access in airports, airplanes and public places.

Google Inc. announced Tuesday that it would provide free Wi-Fi access in 47 airports across the country, including Boston, Houston and Seattle, through Jan. 15. The airports handle about 35 percent of U.S. air travelers, the company said.

Travelers who connect to a wireless "hot spot" at one of the airports will see a browser page that gives them the chance to donate to three charities and have the donation matched by Google.

The 47 airports include some, such as McCarran International in Las Vegas, that already provide free Wi-Fi. Sponsorships help the airport keep the service free.

Google is also providing free Wi-Fi on Virgin America flights for the same period.

EBay Inc., the Web auction powerhouse, will provide free Wi-Fi on some Delta Air Lines Inc. planes during the week of Thanksgiving. Logging on will take users first to eBay's holiday page, but they will be free to roam from there.

Since September, Microsoft Corp. has given away Wi-Fi access at some hotels and airports, encouraging users to make a query on the company's new search engine, Bing.

On Monday, Yahoo Inc. said it is giving away Wi-Fi access in New York's Times Square. One street of the busy area was converted into pedestrian zone with lawn chairs this spring, giving more of a reason to dawdle and perhaps flip open a laptop.

Boingo Wireless Inc., which operates for-pay hot spots in airports and is part of Google's project, said it has been getting good results with free Wi-Fi campaigns sponsored by hotel chains. The campaigns typically offer users 15 to 20 minutes of access after they watch a 30-second video advertisement.