A latest research by Nielsen analytics firm has ranked Facebook as the number one smartphone app for 2013, while Instagram has toppled Twitter with more than 1 million average monthly smartphone users.

Facebook has proved its dominance over other social networking sites with more than 1.2 billion users, and has shown once again that it is the most popular app among smartphone users. The social networking giant has more than one reason to celebrate its reach to the audience. Analytics firm Nielson has collected data of the top 10 popular smartphone apps of 2013 and has crowned Facebook as the "Top smartphone app of the year" with an enormous lead of over 27 million unique monthly smartphone users.

According to Nielsen's data, Facebook and Facebook-owned Instagram comfortably overtook rival Twitter in terms of unique monthly smartphone users.  The results are based on the data collected between January and October 2013, for average monthly unique users aged 18 and above for apps on iOS and Android.

Although Facebook had a bigger win, Google services dominated the top 10 list with its Google Search holding onto the second place with 76 million average monthly unique users, Google Play (73,667,000) on third, YouTube (71,962,000) on fourth, Google Maps (68,580,000) and Gmail (64,408,000) on fifth and sixth position, respectively.

Twitter came in tenth with a monthly audience of 30.8 million, compared to Instagram's 32 million. This also makes Instagram the fastest-growing smartphone app of the year with 66 percent year-over-year increase. Apple's Maps is the second-fastest growing app, with its audience increasing 64 percent year-over-year with 31.8 million smartphone users accessing the app from their phone on a monthly average.

In official terms, Twitter hosts an audience of over 230 million users, compared to Instagram's 150 monthly active users. The survey does show how Instagram is slowly gaining  strong ground in the competitive market and proving a big win for Facebook's $1 billion deal.