As an author, you will have a range of people read your books before and after they’re published.
Your Alpha reader, the first person who reads it, might be a spouse or critique partner. Someone you trust and who you feel comfortable sharing your writing with quite early in the process, perhaps as you write or immediately after finishing the first draft (or a later draft if you’re more comfortable with waiting).
Beta readers, however, will generally be people you don’t know initially. Although at the start of your writing journey you might turn to trusted friends who you know have a critical eye. Possibly writer friends from the community. They are a small group of readers who represent your market.
They will usually read the manuscript when you’re more or less done with it. It can be before or after a professional developmental edit but would usually be before a copy or line edit. This is because you will be looking for big changes that you need to make to the story from your beta feedback. So do this before paying for a detailed line edit. That step comes later.
Your beta readers are looking for plot holes, character arcs, tone, pace. All the things a developmental editor would look at, but from the point of view of a regular reader, rather than a trained eye. Before you pay an editor, you can save yourself some money by using beta readers and may decide not to hire a developmental editor at all if your beta readers are really helpful.
You can then take their feedback and choose what, if anything, to incorporate. If you have 6 beta readers and 4 of them make a similar comment about a secondary character’s behaviour not fitting with the plot, then take that on board and consider changing it.
But if one person says the whole story is garbage while the others all love it, then don’t take that one critical view too seriously!
Beta readers help you to figure out if what you’ve written is marketable and up to scratch.
They are a separate, but sometimes overlapping, group to your advanced review team, who will read the completely finished and polished book right before launch.
It’s up to you how many beta readers you have, but consider keeping the group quite small. Too many voices will make it harder to use their feedback constructively as you can’t possibly please everyone all of the time. They should be people who like to read in your genre who will be considerate but honest too.
It helps to prepare a list of questions for them to answer so that you can coax specific feedback from them. A beta reader whose only feedback is “I liked it” isn’t really helping you. You want specific and constructive comments from them.
Questions about specific themes, characters or plot points will give the beta team things to think about and focus their comments on. Of course, you want them to think beyond the scope of your questions too, but some guidance to get them started will help you to get the most out of this step in the process.
I hope this helps. Any questions, please drop them in the comments and we’ll do our best to answer them!