The first such ad, appearing Monday in color, was bought by CBS. The ad, two-and-a-half inches high, lies horizontally across the bottom of the front page, below the news articles and a brief summary of some articles in the paper. In a statement, the paper said such ads would be placed "below the fold" - that is, on the lower half of the page.

In the past, The Times has printed an occasional front-page classified ad - two or three lines of text at the bottom of the page. And a few years ago it began selling display ads - which are much larger and can combine images and text - on the front pages of sections inside the paper.

But The Times did not sell displays on the first page of the first section, a move regarded by traditionalists as a commercial incursion into the most important news space in the paper.

Most major American papers sell front-page display ads, including The Wall Street Journal, USA Today and The Los Angeles Times, but some others, including TheWashington Post, do not.