Selenium is a suite of tools to automate web browsers across many platforms. WebDriver, part of that suite, is a web automation framework that allows you to execute your tests against different browsers.
Web testing is`mission critical for big business and it's becoming more complicated with each passing day. With WebDriver you can create robust, browser-based regression automation suites and tests scale and distribute scripts across many environments. It also enables you to use a programming language in creating your test scripts and is the core technology in many browser automation tools, APIs`and frameworks.
Selenium WebDriver 3: Level 1 Fundamentals of Automation Testing
Selenium WebDriver 3: Level 2 Implementing Test Automation Frameworks