Every industry has superstars. When it comes to online ad revenue, Facebook and Google are on the red carpet. The digital marketing world often refers to the two as a "digital duopoly" due to their massive success over other social platforms, and the title is warranted.

It's hard to blame anyone who confuses Google AdWords with Google AdSense. The two services have similar names, and they even serve different sides of the same advertising coin.

But before you take advantage of either of these valuable marketing resources, it's important to understand the advantages of AdWords vs. AdSense, and how each platform can benefit your marketing strategy. When utilized correctly, both platforms can help brands optimize their ad spending and even generate revenue to fund additional campaigns. Here's a look at how AdWords and AdSense can help your business raise its standard for digital performance.

Your client sells pizza, but it's not just any old pie. They've created a buffet of gourmet toppings, imported cheeses and homemade sauces that allows customers to build the most unique flavor combinations known to carb lovers anywhere. You know there are plenty of hungry customers out there, so you decide to use retargeting to corner the market on all those "pizza near me" local searches.

So what is retargeting, exactly — and how does it improve your SEO and SEM strategy?

When it comes to your search engine marketing (SEM) strategy, choosing the right keywords can make or break a campaign. From the content you create to the ads you publish, every asset should center around a core list of keywords that align with your target audience's needs.

Whether you're new to running SEM campaigns or consider yourself a seasoned pro, you've likely spent a great deal of time considering what keywords will drive the most clicks and conversions. But what about negative keywords? That is, the keywords you don't want to rank for.

Let's take a look at how a negative keyword list can help improve the success of your SEM efforts.

Marketers know the importance of choosing the right keywords, selecting relevant audience filters and building a landing page that turns referrals into conversions. But if you're serious about PPC campaign optimization, then you also have to spend time hammering away at your campaign's ad copy.

When it comes to pay-per-click (PPC) advertising, driving positive ROI is every marketer's goal. If you're seeing diminishing returns from your PPC campaign strategy, a number of factors could be causing this negative outcome. Take some time to revisit those campaigns and see if you're making one of these common mistakes.

You're Not Using Long-Tail Keywords

Businesses like Target, Wal-Mart and Best Buy might see big returns from ad campaigns focused on broad, popular keywords like "iPhone" or "laptop," but this type of approach typically isn't useful for small or midsize businesses. Research compiled by eConsultancy found that around 70 percent of search traffic comes from long-tail keywords that are at least four words in length. If you haven't already, it may be time to examine your local market and determine what sort of specific, long-tail keywords people use when searching for your business.

Paid search has plenty to offer small and mid-sized businesses, especially when those brands aren't ranking at the top of their desired keyword searches. But spending for this ad space needs to be carefully done so that you aren't throwing away all your marketing dollars. And even when you find the right bid opportunity, there's more work to be done: You need to have strong ad copy in place to take advantage.

When customers keep their activity online, this attribution is easy to track. Even activity across multiple devices can be properly attributed to its source marketing content. But things change when customers leave the digital realm: Offline marketing results are more challenging to accurately attribute. Too often, marketers are forced to either estimate the offline impact of their SEM, social and other digital campaigns, or they don't factor them in at all.

This creates a distorted view of how these channels are driving returns on investment (ROI). Accuracy in measuring ROI is essential in helping you know how to allocate your resources. Fortunately, improved approaches to offline marketing make it easier to pin down concrete numbers.

Remaining relevant and visible is a top objective for any search marketer, which means maintaining prime positioning where online search factors into the customer journey.

However, the role of search has changed over time. In the past, search was seen as a bottom-of-the-funnel activity, rather than something that permeates every stage of the journey. Today, we know that isn't the case. Customers depend on search at every stage leading up to the transaction, which means search strategies must be built to account for these varied stages, too. A diversified approach is required for brands to generate positive results from across the spectrum of customer search activity.

Just as search engines tweak their algorithms, an SEM campaign strategy needs to adjust accordingly. Google and other search engines continually work on improving algorithms and connecting consumers with the information they seek.

If you follow the rules and keep up with these changing demands, you can use this evolution to your advantage. Here are four crucial reminders for SEM this year:

1. Acquaint Yourself With Schema

Schema is a way of organizing data developed and promoted through Schema.org, and the way it works is simple: If you've ever typed in a Google search result that delivers the answer to a question in a text box above the search results, that's the product of Schema. It uses structured data to give on-page information context that Google uses to seek out simple search query answers, according to Search Engine Watch.