If an attributes value had to be same across all the instances of the same class , static keyword is used.
For example if the Minimum salary should be set for all employees in the employee class, use the following code
private static double MinSalary = 30000;
To access a private or public attributes or methods in a class, at first an object of the class should be created . Then using that instance of class , attributes or methods can be accessed. To access a static variable, we don't want to create an instance of the class having the static variable. We can directly refer that static variable as shown below.
double var = Employee.MinSalary