HOW TWITTER MAKES MONEY

This is a really interesting observation I've had for a while now.How does twitter earn money?
While Google - the internet search engine giant has a massive advertisement business model ( adsense,adwords etc besides various other products),and so does Facebook which also has an enormous advertising business model,both of which pumps up massive funds for these two social media giants.The third,however i.e the popular social media giant Twitter donot have any business model to speak of.Atleast not that I know of or that which can be seen from the naked eyes.Theres no advertisements on the entire website ( which could've made them filthy rich with the popularity that the site enjoys ),and also there is no premium memberships on twitter too ( generally seen in other social media or other member based websites which gives access to special features/content to its paid members for a fee ).Twitter has neither!Aint that weird?I wonder!!
How is the website with millions of members in it ( and growing everyday ) surviving for so many years (5+) with no visible streams of income?Dont they have any bills to pay and a few employees to feed as well?How is it possible to exist and survive without any type of income generation by the website?Wasn't the website made in the first place to earn money?Any member based website is generally to maximise profits via the streams of income mentioned above!
However,twitter has so far shied away from advertisement of any type on it nor is it keeping a premier membership model.So it is but obvious to wonder how on earth do they earn money and keep the website up and running!

A little study reveals that twitter do earn money but not through the usual visible streams.It seems as though someone is pumping money from outside into twitter to keep it afloat.They are investors who have invested their money into the twitter project.Such investors are called “venture capitalists” or VCs.VCs are companies where wealthy individuals or organizations bring their money together to help fund companies.Facebook, Google, and YouTube are all companies that received VC funding to help get launched.Twitter has gone through various rounds of raising money till now from VCs.Investors give Twitter money in exchange for partial ownership and the rights to a cut of future profits (if there are any). Read Here
However,there are a few other business models twitter could adopt to diversify their income streams eg.Run advertisements on the website,or start a premium paid membership ( where basic service is free but there is also additional premium service/content for paid members )or twitter can even start a service like "yammer" who earns money from companies by giving them the same type of service ( internal twitting within the company for employees ).Yammer charges the companies a fee in order to obtain the administrative rights to their company’s Yammer account.
Twitter does have some plans to earn money for the future - Read Here
Lets wait and watch what it adopts!

Compared to a year back when this blog was first posted, there are indeed some ways twitter is generating money now-a-days as we can find below :

Twitter sells it’s tweets related to a particular topic to search engines.

Twitter sells the rights to publish live tweets on any hot, trending topic.This is a flat-rate, daily sponsorship that drives huge amounts of impressions, engagements, and clicks. Search engines get live data, and unique comments through each tweet and Twitter gets more users.

Twitter also earns via “Promoted Tweets”. Advertisers pay Twitter to show their tweets in top search results, along with their company name.

Twitter earns via Promoted Accounts which are keyword-targeted, cost-per-follower ads where target is based on what they talk about and who they follow.