"Hearts? Really Twitter? Why not lollipops, or sugardrop fairies made of rainbow smiles, sparkles, and a generous dollop of dreams?" one user wrote.

"There are too many love hearts on Twitter now, I feel like I'm reading text messages between a 12 year old couple”, another tweeted.

Twitter said the move was designed to be easier to understand for users around the world.

"We want to make Twitter easier and more rewarding to use, and we know that at times the star could be confusing, especially to newcomers," product manager Akarshan Kumar said in a blog post.

Kumar said the heart "is a universal symbol that resonates across languages, cultures and time zones."

"The heart is more expressive, enabling you to convey a range of emotions and easily connect with people. And in our tests, we found that people loved it," he added.

The heart symbol had already been used on Twitter's Periscope livestream app, and it now will appear on Twitter and Vine, the app for short videos.

The idea has been around for months, and key Twitter investor Chris Sacca suggested such a change in a June blog post, saying favorite was 'too strong a word'.

"Favorite is a superlative. It implies a ranking. In the early days of Twitter many of us interpreted the word literally and only keep a few tweets in our favorites that were truly, well, our favorites," he wrote.

Some critics said the change puts people in an awkward position of liking tweets related to tragic news events.