[FunkyMonkey]

I've done a few brews now and have never used a started of any sorts. I've used smack packs and dry yeast that I have just sprinkled on the chilled wort. All my brew, so far, have come out okay and have fermented. What would be the benefit of using a starter with a little wort.

[reverseapachemaster]

Healthier fermentation and everything that goes along with it. This question would probably be a good opportunity for the search function. You'll find way more useful information than can be summarized here.

[Stevie]

Article from the main page.

https://www.homebrewersassociation.org/how-to-brew/make-yeast-starter/

[kramerog]

Frequently, it is not necessary to make a starter with dry yeast for 5 gallon ferments.  If your liquid yeast is super fresh, you generally won't have to make a starter.  As your volumes, yeast age or original gravity go up, the need for a starter increases.

[duboman]

Rehydrating dry yeast is always a good practice. Making a proper sized starter with liquid yeast is also beneficial.

An 11g pack of dry yeast is generally always adequate for most 5 gallon batches at most gravities. One smack pack of liquid is considered good for an OG of 1.030-1.040, anything more and a starter is recommended.

Proper pitch rate and temperature control will greatly improve your final product!

[brewinhard]

I rarely get super fresh packets of vials of liquid yeast so making starters is essential for pitching enough viable healthy yeast for a successful fermentation and providing my brewing with the best shot at tasting its best. 

[thetooth]

How: You are basically pitching your yeast into a small batch of weak unhopped wort to allow the growth phase to increase your cell count for a day or two.  I prefer to pressure can starter, but that's just because I'm too lazy to boil a new one every time.

Why:
1. Achieve proper pitching rate for the best possible outcome for your beer.  This is especially important for lagers and high gravity ales.
2. Lower lag time.  Pitching an active yeast starter will promote a faster active fermentation in your batch of beer than pitching directly from vial or packet.
3. Test viability of older yeast.  If you get no activity, you know the yeast is bad before you waste time with a full batch of beer.