Few vs a few - what's the difference?

A few - a small number, but enough. Slightly positive.
"I have a few friends here." (some - it's okay, I'm not alone)
"A few people offered to help." (not many, but there were some)
"Can I ask you a few questions?" (just a small number - reassuring)

Few - a small number, and not enough. Slightly negative.
"I have few friends here." (almost none - implies loneliness)
"Few people offered to help." (almost nobody - disappointing)
"Few companies can match their quality." (only a handful - implies rarity)

Can you swap in "some" without changing the meaning significantly? Then use a few. If the tone is "not enough" or "almost none," use few.

Same pattern with little/a little (uncountable):
"There's a little hope." (some hope - positive)
"There's little hope." (almost no hope - negative/pessimistic)

Few without the article sounds more formal. In casual speech, people tend to say not many instead:
"Not many people showed up." = "Few people showed up." (formal)