how to make bash error outputs code example

Example 1: bash stderr null

command > /dev/null # stderr
command > /dev/null 2>&1 # stdout and stderr
command &> /dev/null # stdout and stderr

Example 2: bash redirect output to null

command > /dev/null
#Example
echo "Hello World"
Hello World
echo "Hello World" > /dev/null
#Doesn't show anything