In recent years, the popularity of social networks has seen the emergence of the social media influencer. Influencers have large followings on social networks, and are often hired by companies to promote their brands.

This type of advertising, which is similar to a product placement in a show or movie, is considered more personal and less invasive than traditional advertising. Influencers use a wide variety of social platforms, but a recent survey by influencer platform Zine found that Facebook's (NASDAQ:FB) Instagram was still the favorite.

A chart comparing the most popular influencer platforms.

Data source: Zine. Total exceeds 100% due to rounding. Chart by author.

Instagram, which had 800 million monthly active users as of last September, offers a simple and visual way for influencers to deliver messages via single photos and short videos. The total number of influencer posts on Instagram also nearly doubled annually to over 1.5 million posts in 2017, according to influencer marketing firm Klear.

Traditional blogs remain surprisingly relevant, thanks to their dedicated followings. However, the three other platforms -- YouTube, Facebook, and Pinterest -- aren't attracting influencers. That's likely because YouTube videos require more time to produce, Facebook's News Feed prioritizes family and friends, and Pinterest is more frequently used for pinning personal interests than following influencers.

Leo Sun has no position in any of the stocks mentioned. The Motley Fool owns shares of and recommends Facebook. The Motley Fool has the following options: short March 2018 $200 calls on Facebook and long March 2018 $170 puts on Facebook. The Motley Fool has a disclosure policy.