What is the grouping of thing together based on specific characteristics called?

Answer 1

This is called classification.

We classify things all the time in our daily life. A trip to the supermarket would be a nightmare if the canned goods were not classified together or if the beef was in with the veg etc.

Classification systems need to be purposeful and useful. One could group confectioneries together by colour but it is better to do so by flavour/style/size etc.

Similarly when it comes to classification of living organisms one has several possible approaches. Looking at very overt characteristics such as colour would be fruitless as often colours are shared by a variety of different species or not even shared within a species.

Even looking at overall morphology is a somewhat misleading method of classifying living things as using this method one would end up putting sharks and dolphins in together.

Modern classification of organisms takes a rounded approach looking at the whole organism, internal, external, behavioral and genetic characteristics. Thus we put mammals together and within that order we then separate out the primates, cats and so forth.

Classification starts with shared characteristics but useful classification looks also at the relationship between the things being classified.