Why some people say Wikipedia is incorrect information?

Wikipedia always accept the good quality and real content, if someone tried to ad fake or promotional content, they block them, so question is how they share incorrect info.I think someone wants to discredit wikipedia, then they spread rumor, wikipedia shares wrong content.

Anyone can edit it.  Thus, at any given time, the information you see may be inaccurate.

because people can edit it. They edit some info for own facilities And Wikipedia need some specific time for resolve it. Most of the time its not safe of this reason. 

For most uses it's accurate. The problem is that it's not monitered. So there is no panel of experts to check on facts. But the articles agree with other sources that I read.

No official board of 'fact checkers'.

Wikipedia also helps me in my school stage, but some people edit this information on any topic, by recommendation always read various sources.

For the most part, Wikipedia is accurate enough. It's not much MORE inaccurate than say, an outdated encyclopedia from the library. However, since anyone can edit articles in Wikipedia, it tends to get a bit muddled at times. 

Nothing is actually perfect, but i've got some ample information from Wikipedia before. Hence we all know the content on Wikipedia are created by people so, discrepancy of some information are inevitable.  

Wikipedia is accurate. But one time I came across a war article, and under the subheading "Casualties and Losses' some troll took out the death figures and replaced it with just "hey". But of course soon it was taken down.

Double check it against other sources. The fact anyone can edit it is both its strength and a vulnerability. If you are - say - doing a paper on World War II and someone has just decided to be a smartalec and edit an article on Pearl Harbor to say Napoleon nuked the Germans there, and you quote it, well... you're wrong. 

Because of the "edit wars" that can occur.