ok so I'm writing a story in the fourm of a diary and I was considering putting spelling and grammar mistakes in on purpose to make it more realistic. Nothing major to the point you can't understand it but just here and there.
I wouldn't, unless there's a real point to it. Like, in Flowers for Algernon the decline in the writing mirrors the character's decline. But it was still irritating to read! Having the irritation without the point? It wouldn't work for me as a reader.
Grammatical mistakes could work, as a diary is, I suppose, a form of first person or monologue. I'm not sure I could (or would) read a whole book of that; perhaps a short story... But spelling mistakes don't really make sense, unless you're planning on some font that would make it look like the real diary (also not recommended). I think these sorts of things are better left alone until one's story-telling is at a very high level (because otherwise why would a reader put up with it?).
I wouldn't do it. The book will be in a binding, or on an e-reader, and so it obviously isn't a diary that you dug out of a trunk somewhere--it will have been published. Adding errors that an editor would clearly catch before publication is likely to break the illusion, rather than enhance it, because it will emphasize the largely unreconcilable break between the fictional reality and reality.
Spelling and grammar mistakes jar me out of story absorption mode back into "holding a book" mode. I think in general, you want to remove all the barriers to a reader becoming absorbed in your story, and for that reason I would say no, do not include them. On the other hand. You could possibly have one, commonly misspelled word misspelled in your story, and then have the diary keeper remark that they had seen the word spelt correctly today and realise they have been spelling it wrong? Or just a couple - all the same misspellings. As an idea. Maybe? My preference would be for no errors.
This reminds me of the film The Pursuit of Happyness. Irritated me all the way through...and that was the punchline of the whole film.
I think it could work. As long as every word isn't garbled so the reader can understand it, it'd be fine. I mean, it's dependent on taste - some people would absolutely hate it on principle. But who wants to appeal to everyone, right? :>
No. Please don't. I'm begging you, on hands and knees even. It muddies the water of your work. I honestly believe Flowers for Algernon MIGHT be the exception that proves this rule.
Sapphire's novel Push is full of spelling mistakes and it's an amazing novel. It didn't jar me at all. Heinlein's The Moon is a Harsh Mistress has done away with loads of articles, for example, and while that was slightly jarring to me, the novel still works. So yes, you can do this, but perhaps in moderation... The writer could misspell commonly misspelled words or use words that are often mixed up for the sake of authenticity, but I can't say if this will work for you without reading what you've written. Novels in the form of diaries are usually written without spelling mistakes, though, so I don't think mistakes are necessary unless you want to show your protagonist's education level is not very high (Push) or she's quite young or if language has evolved to the point where what we'd consider mistakes now are totally ok (Harsh Mistress) or [insert some other reason].
Do the spelling mistakes work in The Moon is a Harsh Mistress if it's Heinlein's first book, and not a bit of a classic? I get the examples and they are great (been decades since I read Heinlein's) but is it going to be an apples to apples comparison? If you are an established author with a few books under your belt, I'd agree far more readily.
Being established has probably helped, yeah. I don't know about the behind-the-scenes circumstances, though, for either of those titles, but if the publisher knows their author's next book is going to be a seller no matter what they write, they're probably more willing to give them more freedoms and take more risks, while a nobody might have to spend a generous amount of time and effort searching for a publisher/agent for their first manuscript. Since writing is a creative effort, I still wouldn't limit myself from certain stylistic choices if I felt they could work for my story.
I say go for it. If you get an agent and an editor that is. If you're going to self-publish you have much less leeway, and trying to make the text as legit as possible is the way to go. Other ideas: Write in attempts at hard to spell words, misspell other words consistently, make an obvious attempt not to use a difficult to spell word, forget the word the writer is trying to use.
If the intent is to make the diary more authentic, then no, you don't need it and it won't lend credibility to the piece. If the misspellings tell the reader something about the character, then you could use that as part of your story telling technique. But keep the reason you are doing it at the forefront of the decision.
There are enough examples in the literary world to justify it, as long as the intent is clear and it doesn't look like bad typographical errors. The publisher or agent should be able to pick up on the intent without explanation. If they can't, it's not working. Grammatical errors would be far more functional than spelling errors, as they can still be accepted as character voice, whereas spelling errors look like typographical errors. My WOP has plenty of grammatical problems. I excuse them as character voice, but the truth is, my grammar is just shit.