EU law restricting website cookies comes into effect
25 May 2011 Last updated at 11:25 BST
The deadline for Europe to introduce a new e-privacy law has passed.
EU regulators want websites to ask for permission before downloading certain types of cookie files.
Cookies are designed to gather information about users, and these rules relate to code designed to help target advertisements - specifically when the information gathered is unrelated to the website being browsed.
But many countries have yet to enact the law.
Julia Caesar reports.