There is 2 different way to handle waits:
1. Implicit Waits
2. Explicit Waits

Implicit Waits: WebDriver waits for an element if they are not immediately available. So, WebDriver does not throw NoSuchElementException immediately. This is known as implicitlyWait(). This can be achieved using: driver.manage().timeouts().implicitlyWait(15, TimeUnit.SECONDS);

Note: If the DOM is get loaded within the wait time it should not wait for the remaining time it
go for the next step,
for an example:Here we wait for 20 seconds, after that it gives NoSuchElementException. If the element present in 5 second then it should not wait for another 15 seconds.

Disadvantages:
(i) In any case, it blindly wait for given seconds.
(ii) Once set, the implicit wait is set for the life of the WebDriver object instance.

Explicit Waits

A. Thread.sleep() : This is to wait the running program for sometime, this can be done using:Ex.- Thread.sleep(3600).

Disadvantages:

(i) In this case, it again blindly wait for given seconds. It is not a better way because if the the
element is present within this given wait time, program does not move further until the wait time
finished.
(ii) Some computers are slow, an element may not show up in a slow computer within the given
wait time.
(iii).It is sleep time for script, not good way to use in script as it sleeps without condition.

Expected Condition

An explicit wait is code you define to wait for a certain condition to occur before proceeding further in the code. There are some convenient methods provided that help you to write code that will wait only as long as required. WebDriverWait in combination with ExpectedCondition is one way this can be accomplished.
Ex.- WebDriverWait wait = new WebDriverWait(driver, 15);
WebElement element = wait.until(ExpectedConditions.presenceOfElementLocated(By.id()));

This waits up to 15 seconds before throwing a TimeoutException or if it finds the element will
return it in 0 – 15 seconds. WebDriverWait by default calls the ExpectedCondition every 500 milliseconds until it returns successfully. A successful return is for ExpectedCondition type is Boolean return true or not null return value for all other ExpectedCondition types. There are some common conditions that are frequently come across when automating web browsers. Listed below are Implementations of each. Java happens to have convienence methods so you don’t have to code an ExpectedCondition class yourself or create your own utility package for them.

– Element is Clickable – it is Displayed and Enabled.
Ex.- WebDriverWait wait = new WebDriverWait(driver, 15);
WebElement element = wait.until (ExpectedConditions.elementToBeClickable(By.id()));

3. Fluent Wait Command: Each FluentWait instance defines the maximum amount of time to wait for a condition, as well as the frequency with which to check the condition. Furthermore, the user may configure the wait to ignore specific types of exceptions whilst waiting, such as ‘NoSuchElementExceptions’ when searching for an element on the page.
Ex.- Wait wait = new FluentWait(driver)
.withTimeout(30, SECONDS)
.pollingEvery(5, SECONDS)
.ignoring(NoSuchElementException.class);
wait.until(ExpectedConditions.elementToBeClickable(By.id()));