1. THEIR – THERE
Use there when referring to a place. For example: There is a good Ice cream parlor at Jones street.
Use their to indicate possession/ownership. For example: Their things were thrown by the landlord.
2. WHERE - WERE
Use where to describe the location or place. For example: The bookstore is a place where people can buy books on every subject.
Use were to describe something that has already happened or is in the past. The word were is the plural past tense of the verb are. The singular past tense of this verb is the word was. For example: The conditions of the construction contract were clearly explained in the legal document.
3. YOU’RE – YOUR
Use your when you mean possession or ownership. For example: Phoebe doesn't look like your sister
Use you're when you mean to expand you are in a sentence. For example: You’re a complete idiot.
4. LOOSE – LOSE
Use loose when you mean “not tight” For example:This knot is indeed too loose.
Use lose when you mean “suffer from a loss.” For example: I believe Agatha is about to lose the race.
5. THIS – THESE
Use this for person or thing that is near the speaker (singular) For example: This orange is smaller than that one.
Use these for persons or things that are near the speaker (plural) For example: These oranges are so ripe!
Even with the lax attitude of social networking sites we should still follow the basic grammar rules and do practice the sometimes tedious grammar check.