CORS is a security protocol that allows web pages to securely access resources from another domain. This is necessary to implement modern web applications that often use data from multiple sources.
By default, browsers prevent web pages from requesting resources from other domains because of the Same-Origin Policy. CORS allows you to bypass this restriction. When a web page makes a request to another domain, the browser first sends a preflight request to see if access is allowed. If the server responds positively, the browser sends the main request.
It is important to understand that CORS does not override the single source policy completely, but only allows you to control which domains can access resources.
Benefits of CORS
- CORS ensures that sensitive data does not fall into the hands of attackers, thereby protecting the server and client;
- CORS enables the creation of web applications that can use resources from multiple sources;
- Developers can create more complex and functional web applications without having to host all resources on a single domain.
Examples of using CORS
- Web sites can download resources such as images, styles, or scripts from other domains, which is especially useful when using content delivery networks (CDNs).
- CORS allows web applications to interact with APIs on other domains, which is widely used in micro-service architecture and integration with external services.
- CORS is used to create dynamic web applications that can update content without reloading the page, receiving data from various sources.
CORS is an important mechanism for modern web development, allowing you to create more flexible and functional web applications while maintaining data security.