Implicitly wait for 20 sec for elements to be present on webpage.

driver.manage().timeouts().implicitlyWait(20,TimeUnit.SECONDS);

Implicitly waits till the page loads for a maximum of 20 sec.

driver.manage().timeouts().pageLoadTimeout(20,TimeUnit.SECONDS);

Implicitly for a max of 20 secs till all Ajax components of a webpage have loaded. This one is useful if a website has a lot of Ajax components.

driver.manage().timeouts().setScriptTimeout(20, TimeUnit.SECONDS