Criminal mischief refers to crimes that are a) non-violent in nature and b) related to the intentional destruction of property that belongs to another person. It covers crimes such as graffiti and vandalism.
In all cases, the damage must be intentional, or the result of recklessness. You cannot be charged with criminal mischief simply because you have an accident of some kind.
While these crimes may seem mild on their surface, they can be charged as anything from a Class A misdemeanor to a class B felony. Punishment can range from 1 year in prison to 25 years in prison. Thus, you should take a criminal mischief charge as seriously as you’d take any criminal mischief charge.