Until now we were able only to search tweets no older than a week. Twitter announced today the plan to enable people to search old tweets. Not all the tweets will be kept for the beginning; for the moment those to be kept will be determined by clicks, retweets and other factors, according to the social network.

Twitter’s Paul Burstein mentioned in a blog post that “the percentage will increase over time.” But the final purpose is for all the tweets to remain on the network at same point in the future.

The company’s change targets the twitter.com domain, the mobile.twitter.com and the Twitter apps, too, iOS and Android.

Another major change is represented by the content from the “Discover” tab. Now it has items such as tweets, trending topics, activity notices and suggestions of new people to follow, all available in a single stream.

There are more than one billion tweets being sent every few days and after six years of Twitter there must be some really history making and interesting tweets. Maybe someone will create a database with different categories of tweets.

Go on Twitter and try finding something significant for your past. It may be interesting.

Will you search old tweets? Do you care if the tweets will be kept or not? Let us know your opinion in the comments box.