Pictures, links and videos will soon no longer count towards Twitter's 140-character limit, in an effort to attract new users to the platform.
Tagged usernames will also not count and users will be able to retweet and quote-tweet themselves to form a running commentary.
New tweets beginning with a username will also be visible to all followers, rather than simply those who follow both parties.
Jack Dorsey, Twitter co-founder and chief executive, said in a blog post: "One of the biggest priorities for us this year is to really refine our product and make it simpler. We're focused on making Twitter a whole lot easier and faster.
"This is what Twitter is great at - what's happening now, live conversation and the simplicity that we started the service with."
Changes to the character limit have been talked about for some time, with previous rumours indicating that Twitter might allow anything up to 10,000-character tweets.
Twitter has failed to grow its revenue in recent years, which has led to moves such as the company hiring a new CEO, integrating live video streaming app Periscope into the timeline, and reordering tweets. Today's announcement is the latest attempt to entice users to the site and grow its user base.
Twitter switched its iOS app from the social media category to the news category without immediate explanation in April, signalling a redirection from the company.
"We're not giving up on the idea of Twitter being in the moment," Dorsey continued. "That concept of brevity, speed and live conversation - being able to think of something and put it out to the world instantly - that's what's most important."
The amendments to the character limit will be rolling out over the coming months, according to the official blog post, giving third-party developers time to update their own products.
