The dictionary definition of an anomaly is something that is different, abnormal, peculiar, or not easily classified. It is a deviation from the common rule. In the context of data science, an anomaly is a data point that deviates a lot from the expected pattern. Techniques to find such data points are called anomaly-detection techniques.
Now let's see some applications of anomaly-detection algorithms:
Credit card fraud
Finding a malignant tumor in a magnetic resonance imaging (MRI) scan
Fault prevention in clusters
Impersonation in exams
Accidents on a highway
In the upcoming sections, we will see various anomaly-detection techniques.