Call me old-fashioned, but the current state of grammar in the world is worrisome to me. Maybe it's our reliance on autocorrect or spell and grammar check, but there is less and less attention to detail when it comes to communication. And as a result, we're all starting to sound like a bunch of idiots.

Personally, whenever I see a simple grammar slip up, I begin to rethink my perception of the person who wrote it. Does this person lack attention to detail? Do the really care about what they're saying? Should I take this person seriously? Do I really want to do business with someone whose writing is worse than a fifth grader?

Sure, when you're sending out hundreds of emails a week and writing social media post after social media post, mistakes will be made. But there's no excuse for not double-checking what you've written. To err is human. To correct your grammatical mistakes, devine.

Don't let a typo make you seem less intelligent. Here's a review of grammar rules many people are confused by or have just forgotten:

1. There, Their, and They're

There refers to a location. For example, "Can you leave the file right there on my desk?"

Their is a possessive pronoun that modifies a noun. For example, "Their work on the project was outstanding."

They're is the contracted form of they are. For example, "They're arriving at the conference tomorrow."

2. It's and Its

It's is the contraction for it is. For example, "It's about time for the meeting to start."

Its is the possessive form of it. For example, "Although the office was in a new building, its roof leaked whenever it rained."

3. Then and Than

Then has to do with time and the order in which events occur. For example, "I had lunch with a client, then I worked on this month's sales report."

Than is used in comparisons. For example, "The new computers were much faster than the old ones."

4. Your and You're

Your is a possessive pronoun that modifies a noun. For example, "Your idea about the the product was the best I've heard yet."

You're is the contraction for you are. For example, "You're sure to be promoted soon if you keep working this hard."

Bonus tip: It's you're welcome, not your welcome. After all, you could also say you are welcome.

5. Effect and Affect

Effect is the result of something. For example, "The quality of the coffee in the break room has a big effect on everyone's moods and productivity."

Affect means to influence. For example, "The news about the merger will affect everybody differently."

6. A lot and Alot

A lot means many. For example, "A lot of people applied for the new marketing position."

Alot isn't a real word. Don't use it. Ever.

7. Loose and  Lose

Loose (rhymes with goose) refers to something that isn't tight. For example, "The chord connected to the modem was loose and that's why the internet wasn't working."

Lose (rhymes with news) is when you misplace something or do not win something. For example, "I don't understand how she can lose the keys to her office every week."

It might seem like there are more important things to focus on than the rules and regulations of the English language. But the fact of the matter is that these common grammar mistakes rarely go unnoticed. And since they're so simple to correct, there's no reason to let them make you seem like an idiot.

What other common grammar mistakes do you see? Share in the comments below!

Ilya Pozin is a serial entrepreneur, writer and investor. He is the founder of Pluto TV, Coplex, and Open Me (acquired by Rowl). Named one of Inc.'s '30 Under 30' entrepreneurs, Ilya also has columns appearing on Forbes and LinkedIn. You can keep up with Ilya on  Twitter.