With a combined 375 million users at the end of 2009, Facebook and Twitter reached more than 25 percent of people using email.
Some pundits have wondered if social media sites like Facebook and Twitter could replace email as the primary form of communication on the Internet. Others point out that Facebook and Twitter’s total user base can never exceed email’s total users since both services, at present, require new registrants to have an email address before joining.
Analyst estimates of the number of total email uses vary greatly from source to source, as each makes assumptions about the number of email addresses each person has and uses. With these challenges in mind, published reports from Email Marketing Reports and Pingdom estimated that there were some 1.4 billion people who had active email addresses in 2009, up 7.7 percent from 1.3 billion in 2008. Email usage is expected to grow an additional 35.7 percent to 1.9 billion by 2013.
By comparison, Facebook and Twitter have much faster growth rates but a smaller total user base.
In 2008, Twitter had approximately one million users, but was experiencing fantastic growth so that by the end of 2009, the micro-blogging service had an estimated 25 million users.
In the same two-year period, Facebook grew from having approximately 140 million users to over 350 million users, a 150 percent growth rate. In the first two months of 2010, Facebook has already added an additional 50 million users, setting a pace to reach more than 650 million users by year’s end.