Grammar! We plough through it in grade school and high school. We're expected to know it well by the time we hit our college campus, and as writers, we are held to the highest expectations in using proper grammar. But as much as we'd like to be viewed as perfect, few of us can accept the award for 100% correct grammar in every piece we write.
That said, I'd like to see writers reach the A level if not the A+ the majority of the time. I didn't mind studying grammar in school. In fact, I rather enjoyed it. My love of words was formed early in my life. I knew kids who absolutely detested the grammar part of English classes. I liked learning the rules and using them. Maybe it's because I'm an organized person and it allowed me to keep things as should be.
Now, many decades later, I get truly irritated when I see poor grammar in public places like written words on a TV screen, or an advertisement, or a story/essay/article written and published with glaring grammatical errors.
I've seen the misuse of your and you're over and over again. It's beyond me that people do not readily see that you're is a contraction of you are and your shows possession, such as your mother, your sweater, your passion. It seems so simple, and yet it is mixed-up by an amazing number of people.
Affect and effect are two more words that are often misused. The easiest way to remember the correct way is that affect is a verb and effect is a noun. So, Age affects the ability to think clearly. and The effects of age can slow us down considerably.
Many confuse they're and their. Again, they're is a contraction of they are while their is a possessive. I heard they're going to the concert tonight to see their daughter perform.
Grammar sometimes seems boring, but I deem it one of life's boring necessities. Pay attention to the little things like this when you write.