Responsive search ads allow you to create ads that adapt to show more relevant messages to your customers. You enter multiple headlines and descriptions when creating a responsive search ad, and over time, Google Ads automatically tests different combinations and learns which combinations work best. This will help you match several different queries, increase your reach, and ultimately get more results from your adaptive search ads. Basically, Google wants more advertisers to use RSA (especially novice advertisers) because it gives its machine learning mechanisms more to work with.
Responsive search ads appear with three headlines and two descriptions at the time they are published, plus a customizable URL depending on the landing page domain and the configuration of the ad's path1 and path2 fields. Each adaptive search ad can contain the following in terms of headlines, descriptive lines, and characters. By contrast, having two ETAs and one RSA per ad group is still the best practice recommended by Google. This is mainly because, due to RSA's machine learning experience, its performance can be variable compared to standard expanded text ads.
This will allow you to continue practicing and optimizing the text of your ads and, at the same time, benefit from Google's ad text tests based on large-scale machine learning. This means that Google will automatically test the different versions of your ad, so you no longer have to microanalyze CTR or impressions. Once your ad is published, you won't be able to change it even if it wasn't as effective as you wanted. Google's reasoning for driving RSA is that it offers advertisers a better way to adapt to changing market trends without having to create individual static ads and test them manually.
In addition, more than 50% of marketers report that their advertising campaigns are 10% more effective with personalization. They're useful for promoting pages that don't have a lot of content (for example, the product page of an e-commerce site), since Google doesn't analyze the content while displaying the ad. This sounds great because you can adjust several headlines and descriptions to better match your queries, but the downside is that you'll lack a bit of control over RSA, since you'll never know exactly what combination of headlines and descriptions Google will choose at any given time. Increasing your reach and, at the same time, increasing your results is one of the main benefits of using responsive search ads.