A major update to Twitter's homepage has turned the micro-blogging site into a real-time search engine tool.

Web users wanting to know what is happening in the world at a given moment can now use Twitter without logging in to the site.

Twitter founder Biz Stone said in a blog post that the redesign is aimed at making Twitter more accessible to newcomers.

"Helping people access Twitter in more relevant and useful ways upon first introduction lowers the barrier to accessing the value Twitter has to offer, and presents the service more consistently with how it has evolved," said Stone.

Twitter's search feature and Trending Topics section are now visible on the homepage, and visitors can instantly view the most popular topics being searched by minute, day or week.

Twitter had originally marketed itself as a "service for friends, family and co-workers to communicate and stay connected", but the new focus is to "share and discover what's happening right now, anywhere in the world".

The new Twitter homepage has a real-time search function

"Twitter has moved from simple social networking into a new kind of communication and a valuable source of timely information," Stone said.

He added that the change in the colours and design of the homepage reflect Twitter's growth from a social networking site to a search engine.

Regular users will not notice the change to the homepage unless they sign out of their accounts.