How does selenium Webdriver work?

first, Let's look at a classic example: take a taxi

In taxi driving, There are usually 3 characters:

• Passenger: he told the taxi driver where he wanted to go and how to get There.

对出租车司机说：1、去阳光棕榈园东门2、从这里转左3、然后直行 200米，第一个红绿灯右转4、再直行 50米，到阳光棕榈园东门5、停车

• Taxi Driver: He is in accordance with customer requirements; Taxi drivers use the steering wheel and car pedal to drive a car to their destination

出租车司机操作汽车：1、插钥匙点火，启动汽车引擎2、开一小段路后左转3、加速，直行200米4、右转，直行50米5、减速停车，到达阳光棕榈园东门

• Car: car performs taxi driver's operation

1、启动引擎2、左转3、直行4、右转5、停车

In test automation using selenium webdriver, there are 3 roles

• Test engineer who writes automation code: runs the automation code to send the request to the browser driver

告诉浏览器 ：1、打开 www.abc.com2、做一个关键字搜索 selenium3、检查实际结果，与预期结果做比较

• Browser Driver: It executes the request of the test engineer and then it sends the request to the browser

告诉浏览器 ：1、给我打开这个页面 www.abc.com2、当textbox显示可见，保存这个web element3、操作textbox这个对象，输入selenium4、当确认按钮可以点击，保存这个web element对象5、点击这个按钮对象

• Browser: it performs a browser-driven request

1、打开www.abc.com2、找到搜索框textbox，输入selenium3、点击搜索按钮4、展示搜索结果

Make an analogy:

• Test engineers are like customers
• Browser drivers are like a taxi driver
• The browser is like a car car rental

Executing the automation script, The following steps are Performed:

• For each selenium command, an HTTP request is created and sent to the browser driver
• Browser driver uses HTTP server to get HTTP request
• The HTTP server determines the steps required to implement the selenium command
• Implementation steps are performed on the browser
• The execution state is sent back to the HTTP server
• An automation script that returns this state on the HTTP server

Reference article:
Webdriver automated testing is like taking a taxi.

How does selenium Webdriver work?