implicit wait vs explicit wait

                                    In Implicit wait, if WebDriver is not able to
locate an element, it will wait for a specified
amount of time for the element to appear, 
before throwing an exception.

Explicit wait is a type of wait , which is used to
stop the execution till a specific condition is true;
We use WebDriverWait and ExpectedCondition classes of
Selenium web driver to implement explicit wait.
Implicit wait is general, explicit wait is applied
for a particular instance only.



WebDriverWait wait = new WebDriverWait(driver, 10);
wait.until(ExpectedConditions.elementToBeClickable(txtFirstname));

                                    Implicit wait is a wait which waits for a specified time 
while locating an element before throwing 
“NoSuchElementException”. As by default selenium tries to 
find elements immediately without any wait. So, it is good 
to use implicit wait. This wait applied to all elements of 
the current driver instance. 
• Explicit wait is a wait which is applied to a particular 
webelement until the ExpectedCondition specified is met. 
• Implicit wait is simply; if condition is met before the timeout, 
it will continue to next step, if condition is not met within 
timeout throw "No Such Element" exception. 
• Explicit wait sometimes we need to wait for a 
certain event/condition such as element is visible, clickable, enabled.... 
driver.manage().timeouts().implicitlyWait(5,TimeUnit.SECONDS); 
webDriverWait wait = new WebDriverWait (driver, 5); 
wait.until (ExpectedConditions.visibilityOf(element);

                                    Mixing both of them can cause unpredictable wait times.

Implicit wait is defined only once in the code.
It will remain same throughout the driver object instance.

Explicit wait is defined whenever it is necessary in the code. 
This wait will call at the time of execution. It is a conditional wait.

Explicit wait will override the implicit wait whereever
explicit wait is applied. So, Explicit Wait gets first preference
then Implicit Wait.