使用Java检查Selenium WebDriver在页面上是否存在或显示元素的正确方法是什么？

I'm testing a web application using Selenium WebDriver and I was wondering which is the proper method to check if the elements are present or displayed. I usually assert that all elements are present on the page but it also checks the hidden elements which in this case would also be necessary to check if the elements are displayed only when some action is done. For example I click a link and other fields and labels are displayed, while they were hidden before. In this case I should both check if the elements are present and also if they are or not displayed before and after some other element is clicked.I'm testing a web application using Selenium We