its about morphemes ,which provides you the full information about this topic. I hope it would be helpful to clear the concept of morphmes

1. Introduction to Morpheme
Types of morpheme
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2. Minimal meaning bearing unit of sound is
called morpheme
 For example
 Encouragement
 En+ courage+ ment
 Disillusionment
 Dis+ illusion+ ment
 unhappiness
 un+happi+ness

3.  Types of morphemes:
 There are two kinds of morpheme.
 Free morpheme
 Bound morpheme

4. A simple word consists of a single morpheme,
and so is a free morpheme, a morpheme with
the potential for independent occurrence.
In “The farmer kills the duckling”, the free
morphemes are the, farm, kill and duck.
 Two kinds of free morphemes:
A. Lexical morpheme: (open class) has lexical meaning;
Examples: N, Verb, Adj, Adv (content words)
B. Functional morpheme (closed class)
Examples: Pro, Prep,
Conj, Art. (function words)

5. Bound morpheme require the presence of another
morpheme to make up a word; they can’t occur
independently. The morphs –er, -s and –ling are bound
morphemes.

6.  There are two types of bound morphemes:
 Inflectional morphemes:
 Derivational morphemes:
 Inflectional morphemes:
 An inflectional morpheme is used to create a variant
form of a word in order to signal grammatical
information.
 For example:The suffix [-ed] signals that a verb is
past tense: walk-ed.

7.  Derivational morphemes:
These are affixes that attach to a lexical root and
result in a new word, a complex lexeme called stem.
The suffix – er , in English is a derivational suffix.
Adding it to a lexical root gives a stem with related
meaning.
Examples: bake – baker, boil – boiler.

9. To sum up, morpheme is a minimal unit of meaning or
grammatical function. It can be full word are part of
word. So to be clear: “un” is a morpheme. “yes” is also a
morpheme, but also happens to be a word. Morphemes
are of two types: free and bound. Morphemes that can
occur on their own are free morphemes, and those that
can’t (e.g., affixes) are bound morphemes. For example,
“cat” is a free morpheme, and the plural suffix “-s” is a
bound morpheme. Bound morphemes are divided into
two types inflectional ( grammatical markers) and
derivational morphemes. Derivational morphemes can
change the class of words , for example ‘teach’ becomes
‘teacher’ teach is a verb but teacher is noun. Sometimes
it maintain the class like friend becomes friendship, they
both are noun.

10. Thanks