Ladies and gentlemen, it’s time to go negative. (And, no, I’m not referring to this year’s presidential race). I’m talking about negative keywords: those words and phrases that are essential to ensuring your pay-per-click (PPC) ads are displayed to the right audience.

Related: 7 Common Mistakes Companies Make With Google AdWords

Going negative: How to eliminate junk PPC queries

Here’s what I mean: You run a small business selling hand-blown glassware; you’ve just launched a new line of wine glasses. You bid on “glasses” as a search term.

Your searcher then Googles a keyword phrase that includes “glasses.” Your ad pops up; the searcher clicks on the ad. Great news, right? Think again: If that searcher is looking for the nearest “glasses repair shop,” for eye glasses, not wine glasses, you’ve just paid money for someone to accidentally click on your ad who has no intention of ever being a customer.

While Google is pretty smart when responding to search queries and integrating user intent into the results, its system isn't perfect. PPC success is predicated on the “Golden Rule of Paid Search”: Give users what they are looking for. As the SEO team at Ranked One has succinctly pointed out, “ Paid search is a pull and not a push marketing initiative. Thus, it is vital that we only present searchers with that which is most relevant to their query.”

Here’s another example from the Ranked One team. Say you want to target searchers looking for “pet-friendly hotels in Albuquerque.” Following standard PPC best practices, you create a PPC ad that includes the search phrase in question (“pet-friendly hotels in Albuquerque”) and a landing page that echoes this message.

But that’s not enough. You also need to eliminate so-called “junk queries.” In this example, you would then remove queries from searchers who have no intention of booking a pet-friendly hotel room -- someone searching for hotel jobs in Albuquerque, for example.

True, a few erroneous clicks won’t sink your PPC budget. But, over time, the lack of a strong negative keyword list means your ads will be shown to the wrong target audience.

How to use negative keywords

Campaign level v. ad group level. There are two ways you can address negative keywords: Add them at the campaign level or the ad-group level. When you add a negative keyword at the campaign level, this tells Google to never show your ad for this keyword. Use this approach for keywords that will never be associated with your product, like “hotel jobs” for your pet-friendly hotel or “eyeglass repair” for your wine glasses.

Related: This Small-Business Owner Increased AdWords Profits by 50 Percent in 60 Days

When you add negative keywords at the ad group level, you tell Google not to show ads at this particular ad-group level. Ad-group level negative keywords can be used to gain greater control over your AdWords campaigns.

Traditional vs. protective use. All of our examples thus far have featured the traditional use of negative keywords -- eliminating extraneous queries that are irrelevant to your product or service. Protective use is a bit different. In a nutshell, you’re restricting the use of a highly specific keyword phrase from general ads, even if this phrase is relevant.

Confused? Kissmetrics offers a great example for PPC shoe ads. In its example, you sell red Puma suede sneakers and create a PPC ad with copy targeted at this particular type of shoe (Ad #1). You also have another, broader catch-all ad for general shoe sales (Ad #2).

In this example, you want to be sure that only people searching for “red Puma suede sneakers” see Ad #1. You don’t want any broad matches for “Puma” or “red sneakers” or “suede sneakers.” So, you add those phrases to your negative keyword list for Ad #1. This ad will then be displayed only to searchers with an exact match for “Red Puma suede sneakers,” effectively beating out all the broad match advertisers.

Building your negative list. When you’re selling a product or service, it’s easy to get stuck in the mindset of what you’re offering. You may be surprised by how ambiguous some of your search terms can be! Not sure how to get started building your negative list? Check out this handy keyword list from Tech Wise that includes a broad range of the most common negative keywords for eliminating erroneous queries, ranging from employment to research.

Next, dive into your queries. Ranked One recommends crawling through search query reports by pulling the SQR right in the Google interface. What phrases pop up again and again that are irrelevant to your product or service? What queries don’t match the user intent you’re targeting? Start your research there.

Related: 4 Key Reasons Local Businesses Fail When Using Google AdWords

Bottom line. Bidding on the best keywords is only half the battle. Negative keywords are just as important for an effective PPC strategy. When used correctly, negative keywords can help you save the budget for the best quality searches.