1.   Both companies aim to develop sophisticated programs that show consumers only those on-line ads likely to interest them, based on their demographics and past surfing habits.

2.   DoubleClick already tracks the Internet surfing habits of millions of individuals, by displaying advertisements on their Web browsers.

3.   Early in the week, the company admitted to collecting personal information on the Web surfing habits of customers using its high-speed Internet service.

4.   Some experts suggest that gender-based channel surfing habits may be hard to change.

5.   The system also prevents the browser from revealing your web surfing habits to eager marketers.

6.   They also track surfing habits and are used for marketing research.

7.   And the software, he said, can be used for much more, including blocking adult and gambling sites without logging surfing habits.

8.   But some critics wonder whether the time saved is worth the hassle of installing another peripheral device to a PC and changing Web surfing habits.

9.   The software collects data on Internet surfing habits, then sends the information to a central computer.

10.   Thousands of Internet users who installed popular software for sharing music and other computer files also unwittingly accepted a program that tracked their Web surfing habits.