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You're in luck. I know a great blog all about those!
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Briefly, for those actually curious: An endogenous retro-virus (ERV) is a virus (the V part) which happens to be of the retro-virus kind. A retro-virus (the R part) is a virus that not only injects it's genetic material into the host's cells, but *also* is able to write that genetic material directly *into* the host cell's DNA in its nucleus. Normally genetic information only goes one way, from the nucleus' DNA out into the cytoplasm as RNA, via a process called transcription. But a retro-virus has the ability to make the opposite happen, called reverse-transcription, so that genetic information gets coded from viral DNA/RNA into the nucleus' DNA. Retro == Reverse. Hence, retro-virus.
So when the virus' genes get written into the DNA of the host, the new host cell is actually a *mutated* version of the host, with an embedded virus in its DNA. Well, if a retro-virus makes its way into the DNA of a sexual germ cell (future sperm or egg), then you can actually end up with an entire organism made entirely of its species' DNA plus the embedded viral DNA mutation.
Usually, the only way for such a mutant child to survive is if the viral DNA gets damaged and shut off before the virus can kill it. But if the child survives and grows to adulthood, they can have children of their own, who will also inherit the broken viral DNA.
When you have a population of organisms who have a broken retro-virus embedded in their DNA at the same spot, we call that an endogenous (the E part) retro-virus. Endogenous basically means: Endo - inside or inner, genous - of or relating to the genes. So, an endogenous retro-virus (ERV) is literally a virus that's been embedded inside our genes, via the process called reverse-transcription. ERV is shorter though.
Cool thing about ERVs? Their pattern of inheritance massively and independently confirms evolution via common ancestor.
[Note: I'm actually not a biologist, I just love biology. I wouldn't be surprised if I screwed up some specifics, but the general idea is correct.]
So when the virus' genes get written into the DNA of the host, the new host cell is actually a *mutated* version of the host, with an embedded virus in its DNA. Well, if a retro-virus makes its way into the DNA of a sexual germ cell (future sperm or egg), then you can actually end up with an entire organism made entirely of its species' DNA plus the embedded viral DNA mutation.
Usually, the only way for such a mutant child to survive is if the viral DNA gets damaged and shut off before the virus can kill it. But if the child survives and grows to adulthood, they can have children of their own, who will also inherit the broken viral DNA.
When you have a population of organisms who have a broken retro-virus embedded in their DNA at the same spot, we call that an endogenous (the E part) retro-virus. Endogenous basically means: Endo - inside or inner, genous - of or relating to the genes. So, an endogenous retro-virus (ERV) is literally a virus that's been embedded inside our genes, via the process called reverse-transcription. ERV is shorter though.
Cool thing about ERVs? Their pattern of inheritance massively and independently confirms evolution via common ancestor.
[Note: I'm actually not a biologist, I just love biology. I wouldn't be surprised if I screwed up some specifics, but the general idea is correct.]