Selenium Core was an integral part of the early versions of Selenium. It was the foundation upon which Selenium RC (Remote Control) and Selenium IDE were built. However, with the evolution of Selenium and the introduction of more advanced components, the role of Selenium Core has changed. Here’s a brief overview:

1. Early Role of Selenium Core: Selenium Core was the JavaScript-based engine that drove the automation of web applications in a browser. It allowed users to write test scripts in Selenese (Selenium’s own scripting language) to interact with web pages.

2. Limitation of Same-Origin Policy: A major limitation of Selenium Core was the same-origin policy imposed by browsers for security reasons. This policy restricted Selenium Core to only interact with web applications hosted on the same domain as the Selenium Core script itself.

3. Selenium RC as a Solution: To overcome the same-origin policy limitation, Selenium RC was introduced. It acted as a server that could proxy commands to the browser, allowing Selenium to interact with any web application regardless of its domain. This made Selenium RC more versatile compared to Selenium Core.

4. Evolution to WebDriver: Selenium WebDriver, the successor to Selenium RC, provided a more robust, object-oriented API and did not rely on JavaScript for automation. WebDriver directly communicates with the browser using the browser’s native support for automation, overcoming the limitations of Selenium Core and Selenium RC.

5. Deprecation and Legacy: With the advancement of Selenium WebDriver, the older Selenium Core and Selenium RC became deprecated. WebDriver is now the standard for Selenium-based automation.

6. Legacy Impact: Despite its deprecation, the principles and functionalities of Selenium Core laid the groundwork for the development of more advanced Selenium tools. It played a crucial role in shaping web automation testing.