Is it correct to use certain special characters when naming filenames in Linux?

Is it correct to use certain special characters, as +, &, ', . (dot) and , (comma), basically, in filenames. I understand that you can use - and _ with no problem, but doing some research I have been unable to find something definite about the other symbols; some say that you can, some say that you can't, and some others say that it is "not encouraged" to use them (whatever that means).