It seems that twitter is constantly evolving and updating its features to improve users overall experience on the favourable social network. We have recently seen the introduction of Advertising on twitter through objective based advertising campaigns. In addition to this Twitter is now changing the content that you are able to see on your timeline.
Traditionally your timeline was made up of a variety of different tweets, favourites and retweets from those twitter users that you follow. However twitter has realised that you might be missing out on a huge variety of tweets that might be of interest and of relevance to you.
Therefore if twitter identifies a tweet that has many favourites, an account that lots of your followers are following or perhaps a tweet that is proving to be very popular it is likely that twitter will now insert this on to your timeline. By doing this twitter is hoping that it will be introducing you to additional content that is likely to be of great use or of great interest to you. Twitter has made it clear that this new feature will not be a means of spamming your timeline with irrelevant and pointless content, as twitter will use a strict process to decipher which tweets will be most suited to you by considering how other people in your twitter network are interacting with these additional tweets.