Correct white balance is very important as it dictates whether colours will look correct in your images. For example a shot taken indoors under tungsten lighting but using an outdoor white balance setting in the camera will look like it has an orange cast on all colours. White surfaces in particular will look very off-colour.

A customer buying one of your images as a jpeg cannot easily adjust white balance without affecting the quality of the image. You can correct white balance most easily if you have shot and processed in RAW format, but it will still be better  done before you submit even if you shoot and process in jpeg.

It is likely most shots you take will be OK on white balance, especially if taken outdoors. Automatic white balance usually gets it pretty close but ideally you will choose the appropriate camera setting for the prevailing light conditions. Indoor shots are always the most tricky and you need to pay particualar attention to white balance in those situations. Tons of tutorials are available in books and on the web.

I just can't understand how so many people get into a photography business without even knowing the basics of photography.   So unprofessional 

I just can't understand how so many people get into a photography business without even knowing the basics of photography.   So unprofessional 

Microstock is for many more than you'd like to believe a hobby, not a business. The name of the forum is Microstockgroup. Yes, there are other, better places to do research about basics like white balance but someone who is new to this forum probably thought that this was a good place to ask. Not everyone is a "professional" microstocker.

An old, but still valuable site to peruse for lighting questions is http://strobist.blogspot.com/ It is helpful for the basics.

Thanks so far for the replys. its really helping me already

and Digital66 ?
im pretty sure, that you didnt started into microstock with everything of the know what you can have.
i got this answer now so often on my different questions.
like a "oh my god how cant you know that, you�re so dumb".
its like i get a answer from god.
you arent god.

and im sure too, that u dont know everything too.

I just can't understand how so many people get into a photography business without even knowing the basics of photography.   So unprofessional 

Microstock also consists of people taking and selling images with their phones, point-and-shoots, etc. So not everybody is in the microstock selling business because they are actual professional photographers, and even know or care what white balance is. They set their phone or camera to auto and shoot.

Don't blame the people asking questions, blame the agencies that allow non-professional, snapshot images. At least the OP is trying to learn.

I just can't understand how so many people get into a photography business without even knowing the basics of photography.   So unprofessional 

  i have to laugh at this . in what business is this you say where the most once reputable agency hire reviewers who cannot understand that it is impossible to have WB during sunset sunrise or in sodium vapour lighting etc. the light is not white during those times.

it is like in that story where a famous master painter asks his student what colour is the cloud. the student says white. the master says , are you speaking from looking at the cloud now, or speaking from remembering the color of cloud?  paint what you see, not what you remember.

in this microstock agency , even professional reviewers don't review from seeing, they review from remembering.  wb is a laughing stock (no pun intended) in this business , really.

"i have to laugh at this . in what business is this you say where the most once reputable agency hire reviewers who cannot understand that it is impossible to have WB during sunset sunrise or in sodium vapour lighting etc. the light is not white during those times."

That's not really what white balance means.

maybe in the procedure of translation from portguese to english, i misphrased the intention of my statement 
what i wanted to say is unless you are prone to doomsdom of producing same old same old studio white flash lighting which are the mainstay of microstock, you are going to be facing a bunch of stuck in the mud mentality of reviewers who would reject anything that does not look white like you get with flash or peak hour sunlight.
we already see how some oldtimers complain of their images shot during certain hours or mixed lighting being rejected for wrong WB.
i know what what wb is, i just don't think there is anything other than white boring studio white
be it bluish cool or orange warm that is considered acceptable wb.
bluish cool orange white is still not absolute white. wb is a hyperbole.