Ad extensions boost clickthrough rates — these extra links and lines of copy make your ads more visible and more relevant at the same time. And when you improve your visibility and relevance, you increase your clickthrough rate (CTR). Here are four of the extensions available and how to make the best use of them:

Ad Extension No. 1: Sitelinks. If your ad is showing in one of the top three premium spots, you can show sitelink extensions. These appear as additional links underneath your main ad. They don’t cost any extra, they offer more specific and relevant options for your prospect to click on, and they let you take visitors directly to the most relevant page. Best of all, they take up more space on the Google results page, pushing your competitors and the organic search listings further down and out of the way. Let’s say your website sells a particular brand of men’s shirts. You bid on the brand name as a keyword and write an ad that specifically offers a deal on long-sleeve crewnecks. With sitelinks, you can also add in three or four additional links in your ad that take visitors to offers for turtlenecks, short sleeve shirts or even hoodies, all from the same brand. Or you can highlight other information that may be of particular interest to the searcher, such as your “About Us” page, or your “Shipping and Returns Policy” page.

Ad Extension No. 2: Call Extensions. In late 2013, Google adjusted their editorial guidelines so you can no longer include a phone number in the headline or text of your ad. That’s actually a good thing, because the phone number option is now available through the call extensions feature instead. Activate this, and the phone number of your choice will appear underneath your ad as an additional free line. That buys you extra space for ad copy and allows your ad to catch more eyeballs by taking up more space on the results page. Call extensions are especially powerful when they show on mobile phones: You can set it so users click on your phone number and connect to you directly from your ad. That’s particularly handy if you have a site that doesn’t display well on mobile devices; better still, if the primary call-to-action on your landing page is to call your phone number. Your contact number will show at the top of your ad in place of your headline, highlighted in blue to indicate that it’s clickable.

Ad Extension No. 3: Location. This is similar to call extensions except that, instead of showing your contact phone number, Google will show your physical location. This is an excellent feature for local brick-and-mortar businesses that want to increase foot traffic to their location.

Ad Extension No. 4: Reviews. This specifically refers to reviews, not by individual buyers, but by reputable media outlets or blogs. This is another extension that’s tricky to set up. To qualify for this, you’ll need the URL of the webpage that contains your review, then either select a direct quote or write a paraphrased version of no more than 67 characters, including the source name. You then need to provide Google with the URL of the third-party site on which the review can be found. And you’ll need to post the same quote on your landing page. If you’re willing to do the dance, once you activate it, this extension will display the review quote as an extra line below your ad.