Some Common Errors of Grammar and Punctuation Hi, and I hope you are all well. Here I would like to codify all the common errors people make concerning grammar and punctuation of the English language, so that it may be of benefit to anybody learning English. I will add more, and others are free to add on, but for now here's a few. You're and Your. YOUR is the possessive form of YOU, denoting [an object or thing] belonging to another. Example 1: Your teeth are very white. Example 2: You and your friend are free to come along. You're is used in addressing another - it is in essence used to mean, 'You are', where the apostrophe denotes the omission of the letter 'a'. Example 1: You're a great friend! Example 2: You're overreacting! Here, instead of saying 'you are', it was said 'you're'. Whereas in the previous case, your was said to be belonging to another. Than and Then. Than is used for comparative purposes, i.e. when comparing two things. Example 1: James is taller THAN Mike. Example 2: I would rather visit Italy than visit France. Here you can see we are comparing two things, (i.e. James and Mike, Italy and France), so we use than. Then is used in sequence of events, to show something occurring, coming after etc. something else. Example 1: In the morning I went to school, and THEN I went to work afterwards. Example 2: First you boil the water, THEN you add in the tea.