Data breaches, often resulting from cyber-attacks or careless practices, involve the theft of sensitive information like credit card numbers and trade secrets, with Bitcoin miners being notable perpetrators. Protecting against these breaches involves understanding and safeguarding 'secrets,' such as passwords and API keys, by removing plaintext secrets from codebases and implementing detection in CI/CD pipelines. It's essential to manage secrets securely through encryption and secret servers, or by utilizing cloud providers' secret management services. Having a response plan for data breaches, including resetting credentials and monitoring systems, is crucial, as is integrating security measures early in the development process. Pulumi emphasizes security by default, offering built-in secret storage and supporting major cloud secret services.