Twitter has announced plans to start showing individually target adverts based on users' browsing history.
The social networking site said it will be "experimenting with a way to make adverts on Twitter more useful" to users by displaying promoted content from brands and businesses a user has shown interest in.
According to a post on its blog, the company said: "Users won't see more ads on Twitter, but they may see better ones."
It said the move, which technology experts say will bring Twitter in line with other social networking sites that tailor adverts, will be trialled in the US "soon".
A spokesman said: "The ad pilot is US-only and we don't have a timescale for roll-out more widely."
Cookie files, placed on web surfers' computers by the websites they visit, contain information about the user such as what sites they have visited or where they are logging in from.
In the case of Twitter, the company will further allow retailers to attach anonymous versions of their customers' email addresses, known as hashes, to Twitter's advertising engine to individually target their customer base.
Privately-owned Twitter, valued at close to $10bn by investors, has ramped up its advertising capabilities ahead of a widely expected initial public offering in 2014.
Twitter's new feature, which is expected to raise advertising rates and revenues for the company, arrives in the midst of heightened public debate over the erosion of online privacy.
In recent years both the European Union and the US Federal Trade Commission have probed the extent of tracking technologies used by sites like Facebook and last year, European authorities began requiring websites to inform visitors that cookies were being placed on their computers.
It also said it would give its users the option of disabling cookies by enabling a "Do Not Track" option in their browser, an option provided by many leading browsers such as Mozilla Firefox and Internet Explorer.
Twitter users can also wholly opt out of ads tailored by outside data by opening their account settings, the company said.