Do you have an idea for a book? Unless you can find a traditional publisher to fund it (no small feat) your only alternative is to self-publish. There are essentially no standards to what can be self-published. Of course, you fund the project yourself. For an overview of self-publishing see http://www.sfwa.org/other-resources/for-authors/writer-beware/pod/.
There are several companies that offer packages for on the order of $4,000. I used iUniverse out of Bloomington Indiana. For one’s investment, one gets the book ID (ISBN), the style of the book and delivery of a print-on-demand (POD) copy. An alternative is to print offset, a process that runs in quantity. With this you get into the inventory management business.
Few authors get by with the standard package. The publisher’s marketing resources all cost extra and it seems to me that they were a total waste. With offset there are also warehouse fees. The average self-published book sells 250 copies over its lifetime. In addition the eBook competes with the hard copy.
I made a terrible mistake, aided by misinformation about royalties from my book representative at iUniverse, and printed 2,000 copies of my book. For information on the book see https://www.jbv.com/8steps. This site also contains a link to purchase the book. After I realized the mistake I tried to back out, and the vendor was extremely uncooperative. I took them to small claims court and got close to half of my purchase returned.
So, what advice would I give? Don’t print offset. Live with the POD even though the return is less. Do more research than I did; there are less expensive alternatives, particularly if you are comfortable managing your own marketing. Choose an underserved topic; mine is about business startup and the selection is huge.