The Internet Explorer 6 browser is being used less and less, but still is the kryptonite of web developers due to lack of compatibility with the standards of the internet and the W3C.
IE6 is so beloved by the web developers that there are several campaigns for the death of ie6, as the site http://deathtoie6.com/, this means that many sites insert scripts for not supporting ie6 and recommend you update your browser.
I've worked a lot with ie6 and it's difficult to build sites with the W3C standard and also compatible with ie6, but I have to admit, there are ways (magic and meaningless) to correct the problems with ie6 using W3C standards, but also I admit that patience has limits and often resorted to the famous hacks / fixes (something like "_padding" or even scripts). See how a developer can get after doing the compatibility with ie6:
IE6: The Kryptonite of Web Developers
The dream of every web developer is that the client requests a site and say: "I do not want old browsers like ie6". If this occurs, I can hear a voice: "Oohhh". Of course we also need to verify the customer's environment, because sometimes there's no way. See a fictitious example and can not be confused with reality :-)
You: [Send hate mail to the IE6 team at Microsoft] Well, IE6 is really an outdated browser that has security holes, a rendering engine very poor and very few users out there using it. I don't recommend ie6 support, we can put a bar to the user to update the browser, what do you think?
Client: Did I mention that we service a large restaurant industry, and a lot of the terminals in restaurants still run IE6?
You: [Create a virus to end all computers that have ie6] Ok, I'll have to increase the delivery time.
Client: Unfortunately we cannot postpone the deadline.
You: [Buy beer or soft drinks and snacks for the midnight shift]
It's good to mention that the project managers when selling sites should remember these and several other problems (not just in relation to ie6, but the Web environment as a whole), so he should know about web technology or lead people who may help you with the customer.
I'm not trying to not do what the customer asks, but you need to check what he really needs and provide better products and good market practice. Good communication with the customer will certainly help a lot, but it is moving to other issues that we see in other articles.