Explain the concept of derivation and provide examples.

Derivation is a process in linguistics that involves creating new words by adding affixes to existing words. It is a fundamental aspect of word formation and plays a crucial role in expanding the vocabulary of a language. Derivation allows speakers to create new words with different meanings, grammatical functions, or both.

In the process of derivation, affixes are added to the base or root word, resulting in the formation of a derived word. Affixes can be either prefixes, which are added at the beginning of a word, or suffixes, which are added at the end. These affixes can change the meaning, part of speech, or both of the base word.

Let's consider some examples to illustrate the concept of derivation:

1. Prefixation:
- Unhappy: The prefix "un-" is added to the base word "happy," changing its meaning to "not happy."
- Dislike: The prefix "dis-" is added to the base word "like," altering its meaning to "not like."

2. Suffixation:
- Happily: The suffix "-ly" is added to the base word "happy," transforming it into an adverb, meaning "in a happy manner."
- Teacher: The suffix "-er" is added to the base word "teach," changing it into a noun, referring to a person who teaches.

3. Prefix and Suffix combination:
- Unhappiness: The prefix "un-" and the suffix "-ness" are added to the base word "happy," resulting in a noun that means "the state of not being happy."
- Disagreeable: The prefix "dis-" and the suffix "-able" are added to the base word "agree," creating an adjective that means "not able to be agreed upon."

4. Conversion:
- Email: The noun "email" is derived from the verb "to email" by using the same word without any affixes, indicating a change in word class.
- Bottle: The verb "to bottle" is derived from the noun "bottle" by using the same word without any affixes, indicating a change in word class.

These examples demonstrate how derivation allows for the creation of new words with different meanings or grammatical functions. It showcases the flexibility and productivity of language in expanding its vocabulary through the addition of affixes to existing words.