What makes a collection of people a 'class'? Does grouping people into classes help to explain anything?

Inhaltsangabe oder Einleitung

Class is a concept much used in both sociology as well as everyday language, but it
is surrounded by much confusion about its meaning. There are many different
definitions of class and many different views on how people can be grouped into
classes. In sociology there is an ongoing debate whether or not class is a relevant
concept in contemporary societies and whether it can be used to explain any issues. I
am going to look at the different meanings of “class”. Further I am going to
investigate whether grouping people into classes helps to explain anything.
The use of class to indicate lifestyle, prestige or rank is probably the most commonly
used sense of the term. Here class is bound up with hierarchy, of being higher than
or lower than some other person or group. Rank is often indicated by lifestyles and
particular patterns of consumption. Marx and Weber have provided two of the most
influential explanations about what classes are and how they influence society. Marx
believed that systems of stratification derive from the relationships of social groups to
the means of production. He used the concept class as referring to the main strata in
all stratification systems. A class is a social group whose members share the same
relationship to the means of production with the ruling class oppressing the subject
class. He argued that on the one hand there exists a “class in itself” which is just the
relationship of the social group to the means of production, but on the other hand a
social group only fully becomes a class when it becomes a “class for itself”, when its
members have class consciousness and class solidarity.