Starter yeast question

I'm still a little shady on the topic of starter yeast, is it just brewing a small batch of beer and pitching yeast into it and letting it sit a couple days, then adding it to the fermenter with the wort? Also, when you do brew your main batch do you add the wort to the primary that already contains the starter yeast? Thanks.

Yeast starters aren't usually required if you are pitching a typical 10 or 11 gram dry yeast packet on a five gallon batch of wort. The amount of yeast in one packet is more than is needed to get your 5 gallons of wort off to a good start. For a 10 gallon batch, just pitch two packets.

Yeast starters are most often used to increase the amount of yeast from a liquid yeast pack before pitching, since there will be far less yeast in the liquid pack. The major liquid yeasts in the US come from Wyeast and White Labs.

Wyeast has Activator smack packs with 100 billion yeast cells, and Propagator smack packs with 25 billion cells. The Activator packs don't require a starter for a five gallon batch, although many people make one anyway. They are designed to be directly pitched in five gallons of wort. The less expensive Propagator packs are intended to be used in a starter to build up the number of yeast cells before pitching.

The White Labs vials are also designed for direct pitching in a five gallon batch, but White Labs recommends a starter if your starting gravity is 1.070 or higher.

You'll probably find the yeast companies web sites very interesting, and you can learn a lot about yeast from them. They provide a great deal of information geared toward home brewers, with Q&As, yeast profiles, and yeast starter instructions.

White Labs
Wyeast Labs

I missed part of your question.

Yes, a yeast starter is just a small batch of wort that you use to grow your yeast cells to a pitchable quantity. A wort gravity gravity between 1.040 and 1.052 works well. You don't need hops in it. You can use wort from any source, DME, LME, pressure canned wort from a previous all-grain batch, etc, but Dry Malt Extract (DME) is usually the simplest. It's best to use the lightest DME you can find, as this will be compatible with any beer you want to brew.

Normally you make your yeast starter in a small gallon or 1/2 gallon bottle or a 2000 ml Erlenmeyer flask, or similar. You don't make it in your primary fermenter. After your 5 gallons of wort is cooled down to pitching temperature, you pitch your yeast starter into it from the smaller container.

John Palmer has a good description of Preparing Yeast and Yeast Starters in his online book How to Brew. The book is available online, or you can buy a copy. It's an excellent guide to brewing that every new brewer should read.