In most cases an apostrophe is used to show possession. In such cases, one noun will always be followed by another noun, i.e., the one it possesses. Ex: The cat's master loves his cat. Ex: The men's restroom is closed for repairs.
The apostrophe has three uses: 1) to form possessive nouns; 2) to show the omission of letters; and 3) to indicate plurals of letters, numbers, and symbols. Do not use apostrophes to form possessive pronouns (i.e. his/her computer) or noun plurals that are not possessives.
The Associated Press Stylebook says the correct way to write the possessive case of Chris is Chris', not Chris's. Other style guides, including the Chicago Manual of Style, say Chris's is correct. If there isn't a specific guidebook you need to follow, you can use either Chris' or Chris's.
Use an apostrophe when showing possession
If the plural of the word is formed by adding an "s" (for example, cats), place the apostrophe after the "s" (see guideline #3 below). If the plural of the word is formed without adding an "s" (for example, children), add apostrophe "s" ('s) as you would to the singular form.
Second, a name ending in s takes only an apostrophe if the possessive form is not pronounced with an extra s. Hence: Socrates' philosophy. Saint Saens' music.
Turns out, The AP Stylebook has always called for the opposite: only an apostrophe after a proper name that ends in the letter S. So not only would you write “Moses' wife,” “Achilles' heel,” and “Jesus' disciples,” you would also write “Chris' birthday” and “Jane Strauss' house.”
The possessive
Quick Use: Use an apostrophe + s for singular nouns (sea, sky), common nouns ending with s (tigress, mistress), and irregular plural nouns (women, children). Use only the apostrophe for proper nouns ending with s (Tess, Jesus, Texas) and regular plural nouns (cars, protestors).
The most common apostrophe errors involve homonyms: words that sound like each other but are spelled differently. Let's start with Its', its and it's. Its' is never correct; it is singular, so it would never require a plural possessive. If you're indicating possession, use its—no apostrophe is ever required.
When one person owns something, we use an apostrophe and then an s. This is the most common way that apostrophes will be used, and the easiest rule to remember. If you own it, put an apostrophe on it.
If you're going with The Associated Press Stylebook, James' is the correct way of writing James in the possessive form. But, for all other style guides, James's is the way to go.
In English, the possessive of every singular noun--even singular nouns that end in "s"--is formed by "apostrophe s" with one curious exception (which I'll get to in a moment). Thus "Joe's bike" and "Jess's bike" are both correct but "Jess' bike" is incorrect.
To make a plural possessive, you put an apostrophe after the S: the cats' tails, the houses' roofs. If you make Wilson plural, you get Wilsons. If you then make it possessive, you get the Wilsons' house.
If a name is singular but ends in an “s,” you always add an apostrophe after the name to show possession, but you can also add another “s” after the apostrophe if you prefer (e.g., Jess' office OR Jess's office). If the name is plural, simply add an apostrophe at the end to show possession (e.g., the Jones' new baby).
The possessive of a singular noun is formed by adding 's (whatever the final consonant). Note that some consider Jesus to be an exception to this rule and insist that its possessive be written Jesus'; other exceptions may include other ancient proper names.
The Associated Press Stylebook recommends just an apostrophe: It's Tennessee Williams' best play. But most other authorities endorse 's: Williams's. Williams's means “belonging to Williams.” It is not the plural form of Williams. People's names become plural the way most other words do.
Two people can share ownership of many items and the apostrophe is still used only once. Here, Fran and Liz own all the horses together: At the farm, we rode Fran and Liz's horses.
When making your last name plural, you don't need to add an apostrophe! The apostrophe makes the name possessive. The last letter of your last name will determine if you add an “-s” or an “-es”. If your last name ends in -s, -z, -ch, -sh, or -x, you add -es to your last name to make it plural.
When you meet up with another Harris, we have two Harrises. If you're married, your spouse is Bob Harris's wife. You and your family live in the Harrises' abode. Singulars ending in "s" form the possessive with an apostrophe followed by an "s."
If the name ends in s, z, ch, or sh, you need to add es. That means the Davis family becomes the Davises, the French family becomes the Frenches, the Hernandez family becomes the Hernandezes, and the Glaves family becomes the Glaveses. If the name ends in x, also add es—unless the x is silent.
Do not use an apostrophe in the possessive pronouns whose, ours, yours, his, hers, its, or theirs. Do not use an apostrophe in nouns that are plural but not possessive, such as CDs, 1000s, or 1960s. Do not use an apostrophe in verbs.
The famous nursery rhyme, 'Twinkle, twinkle little star', probably the first one all of us have learnt, is a perfect example of apostrophe.
Show Possession
Singular Possession: The apostrophe comes before the (s). Example: The dog's bones were under the chair. The apostrophe is used to show the single dog's ownership of its bone. Plural Possession: The apostrophe comes after the (s).