This document discusses credit card fraud detection using hybrid models. It begins by introducing the problem of credit card fraud and how billions of dollars are lost to fraud each year. The document then discusses how standard models and hybrid techniques using AdaBoost and majority voting are used to detect fraud. Experimental results on a public credit card dataset and a private dataset from a financial institution show that the majority voting technique achieves good accuracy in detecting fraud cases. The key challenges in credit card fraud detection are also summarized, such as imbalanced data, different costs of misclassification, overlapping data patterns, lack of flexibility, and fraud detection costs.