You've probably never heard of a diaeresis, but seen plenty of them. They dress like little spies that hover around words, cloaked as a foreign invader. What do all the following have in common: Zoë, coöperation, reëlection, Gewürztraminer? All obviously have little floating dots above certain letters, but not all are umlauts. Can you find the spies, the miscreants? I'll give you a tip: if it's not German, it's not an umlaut (in this example specifically).
The diaeresis is an artifact of the English language that, for most purposes, has fallen out of use, unless you are The New Yorker. The diaeresis fits atop a vowel to indicate that it must be pronounced separately from the previous sound. For examples, Zoe would, under regular English customs, be pronounced to rhyme with row, but the diaeresis informs us to pronounce the e separately. The same goes for cooperation, reelection, zoology, etc. In the past, the second vowel received a diaeresis. Unfortunately, history and laziness took over and we got spellings like co-operation, re-election, and eventually we gave up on all that, and now spell them without any artifacts. The same goes for spellings of Chloe and Zoe. Except for a few magazines, books, and the random nerdy blog post, you won't hear or have to worry about those pesky English markings.
But someday, when you're middle-aged and at some drab party with professors and their wives, drop this tidbit and you'll feel just dandy.
Mark Twain once wrote, Substitute 'damn' every time you're inclined to write 'very'; your editor will delete it and the writing will be just as it should be. The best writing uses the best words, and vague words don't cut it. Along with the infamous very, we'll apply the idea of Mark Twain's rule to other words that you should remove or replace.
Very, Quite, Really, Rather: It was very cold outside and we took a very long route, and by the end our noses were very runny. With Mark Twain's tip it reads, It was damn cold outside and we took a damn long route, and by the end our noses were damn runny. The second sentence bleeds with the narrator's voice, but the point is that very is a useless word because it doesn't say anything. If I tell you that it's very cold outside, does that mean it's 70 degrees Fahrenheit and I'm used to desert climates, or that it's 15 degrees and I live in Cleveland? Very detracts more than it gives; it takes more time to say the thought, and it doesn't convey the thought any better. Let's try the sentence again: It was cold outside and we took a long route, and by the end our noses were runny. This sentence is forceful, direct, clean, and takes less time to read. While I like it as is, removing the last very does not result in a good image—perhaps we could rewrite it again: It was cold outside and we took a long route, and by the end our noses dripped endlessly. It's not perfect, but it paints a better image.
Which is correct? Let's take a look at some of the most commonly swapped words and find out how swappable they really are.
Affect vs. Effect: This is an old one, but still worth reviewing. As a noun, effect means "result": The effect of the terrorist attack was war. As a verb, it means "to accomplish" or "to cause": To effect power, we must take it with force. Effect will also be used to convey vague ideas, such as, The climactic effect, its subtle effects, or, if you really want to be annoyed: Its subtle effects affected me. But please don't write such a vague sentence.
Affect, on the other hand, means "to influence": His rhetoric deeply affected one student, who later would become president.
Allusion vs. Illusion: To allude is to make an indirect reference. An illusion is something that is falsely perceived. Steinbeck's East of Eden holds strong biblical allusions. The Fata Morgana we saw is a complex visual illusion.