A modifier is a word or phrase which limits the meaning of another word. For example consider the phrase my bag. We can limit the applicability of this phrase by introducing various modifiers into it: my new bag, my old bag, my expensive bag, my designer bag etc.

Most modifiers are either adjectival (these modify nouns) or adverbial (these modify verbs, adjectives and adverbs).

A modifier should come immediately before the word or phrase it modifies. Although misplaced or dangling modifiers are common in writing, they are incorrect and should be avoided because they cause confusion and alter the meaning of the sentence drastically.
Misplaced Words

A number of single-word modifiers are often misplaced; these include only, even, just, almost nearly, merely, and hardly.

Notice how the meanings of the following sentences change, depending on where you place the word only:

Only David may play with the ball. (David and nobody else may play with the ball.)
David may play only with the ball. (David may play with nothing else.)
David may play with the only ball. (David may play with the only ball there is.)
David may only play with the ball. (David may play – but do nothing else – with the ball.)

Position of the word even

The word even should be written in front of and next to the word it modifies.

Notice how the meaning of the following sentences changes, depending on where you place the word even.

Even Alice could not spot the mistake in the sentence. (Alice, let alone anyone else, could not spot the mistake in the sentence.)
Alice could not even spot the mistake in the sentence. (Alice could not do other things, let alone spot the mistake.)