I should know this but I have become confused and need some schoolin'.

What does an LED's forward voltage actually mean? Is this the minimum
voltage required to forward bias it? Or is it the voltage drop across it? Or
something else?

Whats confusing me is this. From what I understand a forward biased diode
has very little resistance to current. But a google search is telling me
that if I stick a meter across an LED the voltage read will be the forward
voltage rating. How can a device with very little resistance drop voltage. I
was taught that a PN junction typically drops .7 V. So with my current
understanding, if  I have an LED rated at 20mA and a 5V source, a 250ohm
resistor will limit my current to that rated 20mA and my LED will work. Is
this correct?


Also, the datasheet for the PIC16F627 says its capable of direct driving
LED's but the maximum sink current is 25mA. If most leds operate at around
20mA do I really want to run that close to the upper limit?


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