# Wikijunior:Biology/Viruses



## Viruses

!A virus called a rotavirus, which can cause diarrhea.\|alt=Diarrhoea
causing virus,
Rotavirus.
Viruses are much smaller than other living things like
bacteria, so small that it
would take around one hundred viruses laid end to end just to make the
length of a bacterium! Viruses are not really alive. They fall in the
line between living things and non-living things. They do not do all of
the things that living things
do. They can only
make more copies of themselves when they are inside living cells.

Viruses often kill cells, and also make
you ill. Lots of diseases are caused by viruses, the most famous ones
are the viruses that cause the flu, colds, and Covid-19.

