1 - Matching by text
This matches by using either the text on screen, or aria labels. For example I.click("login")  or I.fill("First Name","John")
One thing useful is that when there are multiple text of the same text, it is sometimes useful to do an I.see("Unique text")  near the target text to interact with, think of it as instructing a user over the phone 😉

2 - Matching by HTML/CSS class name
Elements can be selected using HTML/CSS class name, with a dot prefix. For example I.click(".login-button")

3 - Matching by HTML/CSS ID
Elements can be selected using HTML/CSS ID, with a hash prefix. For example I.click("#close")

4 - Matching by XPathElements can be selected using XPath. For example I.click('//*[@id="tsf"]/div[2]/div[3]/center/input[1]')  

Additional Note - Running actions inside an iframe
Finally when interacting with elements inside an iFrame, especially with salesforce, SAP, Shopify. You can improve the accuracy by running actions within a selected iframe context. For example: 

UI.context("#unique-iframe-id", function() {
   I.click("Button inside iframe")
   //... other actions
Did this answer your question?