Everyone hears how WWI started when the Russians went to protect their fellow Slavs in Serbia. But looking on a map, the group of people called South Slavs is separated from Russia and the other Slavs by a few countries. We're these two groups once the same and then somehow another group moved in between them or was there always this separation? Also how are they similar? A lot of Americans like myself have a hard time understanding the differences in ethnic groups among light skinned people. Here you are pretty much just white. So do the regular Slavs and South Slavs share a language, culture and maybe even genetic background or is the relationship more abstract than that?
"Slavic" is a term that describes the peoples that are called that mainly from a linguistic point of view. Various Slavic tribes have migrated south of the Danube around the 6^th century CE.
Today, the peoples that are considered part of the South Slavic group (Bulgarians, Serbians, Croatians, Bosnians, Montenegrins, Macedonians, Slovenes), are indeed geographically separated from the other Slavic countries, such as the Czech Republic, Slovakia, Ukraine, Poland, Russia and Belarus by Austria, Hungary and Romania, nations that are not considered Slavic, even though they have interacted and influenced them from a linguistic and cultural point of view (especially Romanian; its lexicon derives a large number of words from the surrounding Slavic languages).
From a cultural point of view, they display a wide range of quite distinct characteristics, not only when compared to the other sub-groups (West Slavs and East Slavs), but also amongst themselves. The languages and dialects differ considerably: Bulgarian and Macedonian are very similar, but quite distinct from Serbian, Croatian and Slovenian which are mutually intelligible themselves. The large majority of South Slavs are Christian, however Slovenes and Croats, for example, are mainly Catholic Christians, while the rest — with the exception of Bosniaks (which are predominantly Muslim) —, are mostly Orthodox Christians.
Slavs cannot be considered homogenous from a genetic point of view either, with the South Slavs being distinct themselves, even compared to each other. In a few centuries following the Slavs' migration to the Balkan area, the pre-existing peoples were slowly slavicised (with a few exceptions, such as the Albanians, Greeks and smaller groups such as the Aromanians or Megleno-Romanians which preserved their distinct languages) and not replaced completely.
What do you mean abstract?