Subject: Why does heavy resistance draw little current from a circuit?

Here is a quote from my book that i don't completely understand:"Compared to the
resistance being measured, the internal resistance of a voltmeter is designed to
be very high so that the meter will draw little current from the circuit"
I have a couple of questions on this.
1. If the voltmeter has high resistance, won't that resist the current and mess
up the whole circuit?(like I read as an answer to someone's question on this
site)How is this quote true?
2. What is the purpose of resistance?Why would you want to resist a current? 

Re: Why does heavy resistance draw little current from a circuit?