Which statistic indicates how often a click has led to a conversion?
Clickthrough rate (CTR)
Conversion metrics are adjusted to reflect only the ad clicks that could have led to conversions
In Google Ads, conversion an action defined as valuable to your business, such as an online purchase, call, subscription or anything else. Conversions are one of the main factors which show your campaign is successful or not. Especially if you’re focusing on direct impact, not raising brand awareness for example. While conversions number is important, actually it doesn’t show you much. To evaluate your ads and their impact on your business you should calculate the conversion rate.
The conversion rate is the average number of conversions per ad click, shown as a percentage. For example, if you had 100 conversions from 1,000 clicks, your conversion rate would be 10%, since 100/1000*100% = 10%.
Tip: More specific keywords often tend to have a better conversion rate than general keywords.
Read more here: https://support.google.com/adwords/answer/3419241?hl=en