linux - What does "/dev/null" mean at the end of shell commands

Question

What is the difference between the following commands?

ssh myhostname "command1; command2;...commandn;" 2>/dev/null
ssh myhostname "command1; command2;...commandn;" 

1. what does 2> mean?

2. what does /dev/null mean? I read somewhere that result of command will be write to file /dev/null instead of console! Is it right? It seems strange for me that the name of file be null!

Answer 1

2> means "redirect standard-error" to the given file.

/dev/null is the null file. Anything written to it is discarded.

Together they mean "throw away any error messages".