"Quotation marks are doubled like this"
'singles are just calls apostrophes, as is my understanding they are only used when omitting certain letters e.g.
there's (there is, omitting the i)
goin' (omitting the g)
Not sure if thats 100% correct but thats what I thought anyway
Huh? Not any book that I've ever read. Got any examples?US books (and many UK ones now) often use 'the single quotation mark,' as opposed to "the more traditional double" when indicating speech, so single and double are somewhat interchangeable in that sense. Just another example of confusing punctuation! The key is to choose which 'solution' and stick to it (or grab yourself a manual of style).