Clinton pokes a bit of fun at herself, as the caption sarcastically reads "Hard choices," which is the name of her most recent book.

Many Instagrammers were amused, posting comments like "YAAS QUEEN," "ICONIC," and "You're hilarious, I love you," "my girl can joke," while others were not amused, writing "No oldsters allowed on Instagram."

In less than an hour, Clinton has gained almost 10,000 new followers and over 1,000 likes.

A recent Harvard University Institute of Politics poll shows that 83 percent of 18-29 year-olds are on Facebook, 44 percent are on Instagram and 39 percent are on Twitter. After Facebook, Instagram is the most popular social media tool for millennials.

The poll also shows that 55 percent of all young adults, ages 18 to 29, would rather see a Democrat in the White House in 2016.

And in an effort to reach young voters, the Clinton campaign is going where the people are.

There are 300 million Instagram users who share over 70 million photos and videos daily and the 2016 election will be the most visual election to-date.

(CNN)