Manner of articulation is how the sound is made. It includes the position of the tongue, lips, and other parts of the mouth when sounds are made.

The picture below outlines the manner of articulation for many letters.


Again how the tongue and lips are placed to make a sound is the manner of articulation. Consonants sounds are divided into six categories based upon how the air is released or constricted.
These 6 categories will be defined below. Underneath each definition is a link to a chart with audio examples of each manner of articulation.

Stop- No air is released there is a complete closure.
Stop or Plosive plosive consonant phonemes /p/ /b/ /t/ /d/ /k/ /g/

Fricative- There is a small opening for air to be released and air is forced through it.
Fricative Sounds

Affricative- A stop followed by an africative.
Affricative Sounds
Nasal- Air is released through the nose because the mouth is blocked.
Nasal Sounds

Liquid- Air passes freely there is little tightening or closure.
Liquid Sounds

Glide- Slight constriction corresponding to a vowel.
Glide Sounds

Vowels do not fit into the categories above. There are three separate categories for vowel sounds.
High Front Vowels-Sounds made when the tongue is moved up toward the palate and out toward the lips.

High Back Vowels- Sounds made when the tongue is moved up toward the palate and toward the back of the throat.

Low Front Vowels- Sounds made when the tongue is low in the mouth and out toward the lips.

You can see a chart and hear examples of each vowel category at the following link.
Vowel Categories and sounds