Self-publishing online is becoming far more common as authors bypass traditional publishing companies, who publish in the traditional way. The work needs to meet the professional standards expected of a printed book. There are several companies which provide aspiring authors with outlets for instantly printed work, but it is also possible to publish yourself without them.
Making your work professional
Self-publishing online is a growing industry as new technology makes small or single print runs economically worthwhile, or as whole works can be read off the Internet or as an e-book.
If you wish to print your own book, you need to ensure that it meets professional standards. This means that it should be well-written and should be carefully edited. The editor will check for spelling and grammatical errors and also pick up on any areas where you might head into trouble with libel laws, etc.
On demand publishing
While traditional publishing companies printed large book runs and were left with surplus [remaindered] stock, modern technology has made it possible to print and bind an individual book within a short time, and still make a profit on each one. Some companies will print your books and sell them to readers, but some large bookshops now have their own machines that run off copies of printing on-demand books.
The advantages of working through a company
Authors are not always good business people, so while they can often write books well, they are not necessarily good at the marketing/business side of the operation. Creative people often benefit from the help of people with business skills.
The on-demand publishing companies often have sophisticated marketing operations and are able to get your work onto major online booksellers. These booksellers know these companies well and are aware of what books are on their lists.
Companies can be into e-book publishing besides traditional printing, and they may be be able to have the book downloaded into a computer or electronic reader.
Library books placement
They will also take care of the official side of the operation. It is a legal requirement that six copies of every book published in the UK must be sent to the six libraries of record, the national libraries of England, Scotland and Wales, and the libraries of Oxford, Cambridge and Trinity College Dublin. Companies can also get your book reviewed in the press, which is good advertising.
Authors can be totally independent and sell their work via their own website. You must advertise the website in several ways and you will have to arrange your own reviews etc. Unless you want to give the book away, you must make arrangements to receive online payments through the website.