The expectations ahead of Facebook's (META 2.98%) second-quarter report on Wednesday are undoubtedly high. Analysts expect the company to report a whopping 48.8% and 62% year-over-year increase in revenue and non-GAAP EPS, respectively. Investors following the company closely probably aren't surprised by the rosy expectations. Not only has Facebook's revenue increased 46% for the entire trailing-12-month period leading up to this quarter, but the company has also made a habit of crushing analyst expectations.

Facebook CEO Mark Zuckerberg (right) in his office. Image source: Facebook.

But what should investors expect from other less followed, but still important, metrics, such as user engagement, daily active users, and growth of social platforms beyond the native Facebook app? Here's some background on these key areas of Facebook's business ahead of the company's second-quarter results.

User engagement

One key metric Facebook investors should always keep an eye on is the social network's engagement rate, or its daily active users as a percentage of monthly active users. This metric demonstrates how engaged Facebook users are on a daily basis. A decline in user engagement would be a red flag, suggesting users are losing interested in logging into the platform every day.

So far, Facebook's engagement rate has consistently trended upward. Indeed, in Facebook's most recent quarter, the metric hit an all-time high of 66%. This compares with an engagement rate of 63% in the first quarter of 2014 and 65% in the first quarter of 2015.

What should investors expect from the metric in Q2? Expect an engagement rate of 66% or higher. Ahead of the quarter's results, there's no indication engagement on the platform is suffering. Even more, the social network's aggressive rollout of features for Facebook Live, or its live-streaming video feature, during the first half of the year could boost engagement even higher.

Facebook Live. Image source: Facebook.

If the rate declines, investors should look to see if management has a good reason for the pullback during the company's earnings call.

Daily active users

While the media generally focuses on Facebook's reported monthly active users, which hit a record high of 1.65 billion in Q1, investors should arguably be more interested in the company's daily active users. It's this measure of Facebook's more active users that sets the social network far apart from competition. No other similar social network comes even close to Facebook's daily active user count.

In the first quarter of 2016, Facebook's daily active users hit 1.09 billion, up 16% year over year and 5% sequentially. Interestingly, Facebook's 5% sequential growth in daily active users last quarter represented a meaningful uptick from the 3% growth the social network saw in Q4. Going into Facebook's second-quarter results, it will be interesting to see if Facebook's elevated first-quarter daily active user growth was just a one-quarter benefit or a more sustainable trend.

Users on Facebook's other social platforms

Another area that is of increasing importance for Facebook is its fast-growing user bases across its other social platforms. As of Q1, here's where the platforms stood.

Social Network

Q1 2016 Monthly Active Users

Q1 2015 Monthly Active Users

WhatsApp

1 billion

800 million

Messenger

900 million

600 million

Instagram

400 million

300 million

Notably, however, both Messenger and Instagram hit key milestones since the last time Facebook reported first-quarter results. Instagram hit 500 million monthly active users in June and Messenger hit 1 billion monthly active users earlier this month.

But the company has been quiet about where WhatsApp stands, only noting in its most recent quarter the service has more than a billion monthly active users. Investors should Look to see if Facebook management indicates WhatsApp is still growing meaningfully.

Investors can find a copy of Facebook's second-quarter earnings release at the company's Investor Relations page on its website after market close on Wednesday, July 27. Management will host a live conference to discuss its quarterly results at 2 p.m. PT. The call will also be available at Facebook's Investor Relations page.

Stay tuned to The Motley Fool for more pre-earnings Facebook coverage, as well as a Foolish take on the company's results after they are released.