You've probably heard the saying, "When you assume, you make an ass of you and me." No? Well, now you have.
When people hear I'm a writer, I think they assume that I'm amazing at grammar and I should be well spoken. My husband and editor can attest that neither statement is true. I have a mashing of dialects from living in New Jersey, California, Texas and Missouri. I often have to refer back in my kids' grammar books just to grade their homework. I find myself wanting to take back most of what I say. And, for some reason, I think my husband is on the same wave length as me when I ask a random question about something I've just seen. "Um, hello. You should know what I'm thinking. We've been together for 20 years."
This last statement is more true when I think about my kids. The other day, my daughter asked me what "that" building is for. Assuming I knew which one she meant, I told her it stored electrical parts. The very next day, my son asks me what that building is for. I shook my head and told him his sister asked the same question the day before and why wasn't he listening. "No. Not that one. That one." I need to remind you that I'm driving, so seeing them point or knowing which window they are looking at is silly. I explained to them that they need to use descriptive words when asking a question when I'm driving and it was like a light bulb went off.
The same happens in writing. I can't assume my reader knows what's going on in my head no more than my husband knows when I blurt out, "Did you see that?" As a writer, I have to show my readers what's in my head; describe how my character feels and what she sees (my main characters are always female). Proper descriptive words will keep you, as the writer, from making an ass of you and your reader.