Apostrophe

Use an apostrophe (') to denote possession in a noun. Place it

After the complete word when a plural word ends in s.

universities' support
After the final noun in a compound term to show mutual or joint possession.

resistors and capacitors' characteristics
After each noun in a series to show individual possession.

The difference between AMD's and Intel's test results...

Make a number or abbreviation possessive in the same way you would most nouns.

1993's budget
a CRT's refresh rate

Do not use an apostrophe with possessive pronouns.

yours
theirs
whose
its