One of the biggest challenges web developers have is making sure their website works on multiple different browsers, screen sizes and devices. You can ask yourself why are browsers so different and why do you sometimes need to open up Chrome when booking an appointment to hairdressers?
The reason for this is that the web standards that everyone works towards are guidelines and not rules they need to follow. What this means is some aspects of the guidelines are open to interpretations. This is where we get differences in how something you develop and test on Chrome can look very different on Firefox.
As a good rule you should always test your website on Chrome, Safari, Firefox and Opera. Ideally on as many devices and screen sizes as possible. According to StatCounter these browsers are the most commonly used around the globe at the moment.
Browsers to use for development
This question can be answered in so many different ways and anyone you speak to could give you a different response. The correct answer in my opinion is to use the one you are mosr comfortable with for personal use. The reason for this is you know how it behaves and where settings and extensions are.
However some browsers have better debugging tools than others. For example Chrome has great developer tools built in that can be accessed via settings inside more tools.
Firefox has a browser made especially for developers called Firefox Developer Edition that you can find here if you want to download it. The browser specifically made for developers has great features like better debugging and screen size testing. You can visualise any CCS grinds you have (which is a great benefit) and many more.
As a web developer it is important to be open to trying your work on multiple different browsers and devices irrespective of what your personal choice is. The reason for this is users have their own personal choise and they will use what makes sense to them. Even if you think a browser is not commonly used it does not mean that a lot of users are not using it. Take Opera for example. It has a little over 2% of internet traffic worldwide according to StatCounter. 2% of all internet user (4.66 billtion) is still around 90 million people which is a significant amount of potential users you could be ignoring.