Just to chime in here as both of the above answers were great, don't only focus on the keyword being in the title. A lot of the time webmasters will have an extremely "dull" phrase as their title just to include the keyword/phrase.
Keyword in title is important, but if the phrase doesn't initiate a click then you're gonna lose ranking in a circumstance where you're in the third spot and your title sucks, but the 1st, 2nd, and 4th spot the title is more "clickable". Google looks at CTR, so if that 4th spot is receiving more clicks than you are, you will most likely switch positions and unless you are proactive this could spiral a page downwards in ranking.
It happens a lot with ecommerce stores. I have a client who has spa treatment products for a specific distributor. The distributor only does B2B transactions. So only retailers carry the product (you have to own a store and they rarely allow websites to sell their product).
Most of the listings were titles like "Brand Name Spa Treatment | Website Name". Very basic and dull just to include the keyword. I really didn't care about the "spa treatment" KW in the beginning of the campaign as I wanted the KW ranking that was going to produce the most sales immediately. So the Brand name was receiving 320 monthly searches. Our competitors organically looked like:
Brand
Amazon
Amazon
Website with long URL longbrandnamepoolsandspas.com
Then the results below it were terrible.
But the first 4 results just had horrible titles. Brand Name Spa Treatment
Our title read:
20% Off Brand Name w/ Auto-Ship <<<<<< (all re-sellers have this capability)
We out ranked Amazon AND the main company for the keyword. The Brand contacted us to ask us what we did hahahaha. Now obviously we did some basic SEO. And it wasn't anything crazy. Just Web 2.0s, A couple high PR quality PBN and guest posts, and some social. So was it the title being more "clickable" that caused us to move to #1. No tellin' but it definitely was a contributor.
So yes use the keyword in title but do not sacrifice the utilization of "clickable" titles.
The meta description should be utilized just the same. You need copy that will entice a reader to click. (just an FYI)
As long as you're avoiding titles that suck and titles that may cause a user to steer clear of your site (you'd be surprised), while including the keyword, then you're good. Just don't go off making the same mistake as the Brand and Amazon did above. Even when i was in the third position, I'm sure we were soaking up the majority (outside of ads) of the clicks.