Which spelling/grammar mistakes annoy you the most?

Hey man, I also appreciate your passion/interest in this topic - seldom do I come across people that are as fired up about grammar/writing/the English language as I am, lol. Anyway, I very much understand where you're coming from - in fact my best mate has the same argument, and unfortunately neither of us ended up conceding. I first learned my side of the argument from two sources: 1. My university English classes, which included African-American studies 2. My wife, who has a Masters degree in English and Urban Studies, and teaches an inner-city high school with predominately African-American students (my wife and I are white). This is just one example - and I genuinely don't want to get *too* deep right now - but [there's a lot of racism](https://readingpartners.org/blog/black-english-language-based-racism/) in the history of the creation of the English language, grammar, literature, etc. This doesn't have much to do with British English - it is specifically an American problem that I'm aware of - but it is a big, sad problem nonetheless. [Here is another thing to read](https://www.buffalo.edu/ubnow/stories/2021/11/baker-bell-linguistic-racism.html). I don't want to say too much about this topic here as it can get pretty heated, so I'll leave it at that, and just say my one final bit: While there are many obvious mistakes used in the English language - many pointed out in this thread that are blatantlt wrong on both sides of the pond - there is a whole other category of language discussion about certain ways and styles of saying things that requires much more nuance before calling something right or wrong. [This source](https://dictionary.cambridge.org/us/grammar/british-grammar/at-on-and-in-time) states, "Note that American English speakers usually say *on the weekend*. It doesn't say whether that's right *or* wrong. It just says that's what we say, which is exactly my point. American English speakers/writers should avoid some of these speaking/writing "styles" when writing university papers, writing scientific journals, presenting at conferences, etc. Primarily formal texts and speaking events. But in our day-to-day life, especially on the internet, it's just our style.. and it's not necessarily wrong.