Click-through rate (CTR) is a measure of the effectiveness of an online advertisement or link, calculated by dividing the number of clicks on the ad or link by the total number of times it was shown. It is a crucial metric for digital marketing, as it indicates the percentage of people who were enticed enough by the ad to click on it and potentially become a customer. A high click-through rate is generally seen as a positive sign, as it shows that the ad is relevant and engaging to the target audience. However, a low click-through rate may indicate that the ad needs to be revised or that it is not reaching the right audience. CTR is an important tool for businesses to track the success of their online advertising campaigns and make informed decisions about their marketing strategies.