Cross browser testing is the challenge for any software tester as there are endless combinations for browsers, versions, platforms. Dealing with all these combinations is not an easy task as not all web browsers are created equal. Some are exclusively compatible with certain operating systems, while some restrict certain features to specific operating system. Some claim, better rendering over others.
Before going deep down in any topic, we must ask a few questions to understand its core. Questions like What, Why, When, Who and How?
Let's start by answering above questions:
What? : In simple words Cross browser testing is to test your website or application in multiple browsers to make sure that it works consistently as intended without any discrepancy, or compromise in Quality.
Why? : It is required to check appearance and functionality of web page in different browsers to verify whether is it same, different or better than other browser, etc.
When? : It is always good idea to start cross browser testing as early as possible, when page layouts are available. But it can be performed when application is fully functional and available for QA testing.
Who? : QA team will perform the cross browsers testing after getting relevant information from business analysis and design teams who are keen on knowing how the application behaves on multiple browsers.
How? : It can be done manually using multiple machines, OS's and browsers. I can also be done by using tools which are available in the market.
Now answering above questions, will trigger more questions in the mind, such as Is there any checklist that can followed? The answer is "Yes". There is a checklist for Cross browser testing.
Page layout in different resolutions
Page content alignment to center, Left side or Right side
Page zoom-in and zoom-out functionality
Font size validation
HTML or XHTML validation
Ajax and JQuery functionality
Images and Alignment
Header and Footer sections
Date and Time formats
Special characters with HTML character encoding
These checks need to be performed on different browsers, operating systems etc.
Here are some tips on How to improve Cross Browser Testing.