The hamza is a peculiar mark that stands for a glottal stop which is a slight pause where the breath is held when saying a word. Within English, it usually occurs in the middle of a word. Examples include 'uh-oh', 'button', and 'kitten'. When you say these words slowly you will notice there is a quick pause in the middle of them. This is the glottal stop. We don't pay much attention to it English, but within Arabic it is considered a unique sound and uses the special character ء to mark this glottal stop. Mastering the glottal stop will be a key component in learning to speak Arabic like an Arab.
The hamza can be placed anywhere in the word. Its location in the word is generally catagorized into 3 positions: Beginning of the word, Middle of the Word, End of the Word. Each postion has its own unique features as will be discussed below. (Note that the transliteration for the hamza is an apostrophe)
Before getting into the nitty-gritty of hamzas one needs to understand that hamzas generally prefer to be situated on a "seat". The "seat" refers to one of the three long vowels (ا - ā, و - ū, ي - ī). These long vowels act as "seats" and in doing so they lose their long vowel sound, ie. they are not pronounced. There are some words where the hamza sits on its own without a "seat". Now, when the breath is paused with a hamza, the next sound uttered after the pause is going to be a short vowel or no sound at all if the hamza comes at the end of the word which is at the end of a sentence (see pausal form in the miscellaneous section). Because short vowel markers placed over a letter indicate the vowel sound to come after the letter, a short vowel marker is placed over or under the hamza to indicate the short vowel sound that comes after it. The examples below will help solidify the student's understanding of hamzas.
When the hamza comes at the beginning of a word it must be "seated" on or under an 'alif'. There are no exceptions to this. All words that start with a short vowel (and there are plenty of them) make use of the hamza "seated" on/under an 'alif'. Remember the 'alif' is not pronounced and it is the short vowel associated with hamza that is pronounced. You might wonder as to why you need a hamza. Why not just put a short vowel marker with the 'alif' and bypass the hamza entirely. The reason is that it is assumed that a word that starts with a short vowel must initially have a glottal stop in front of it. This makes sense. If you were to say the word "apple", there would be a brief pause and then an explosion of breath as the 'a' sound of "apple" is vocalized.
If the short vowel is a fatɧa or a ɖamma then the hamza sits on top of the 'alif' with the short vowel marker above it. If the short vowel is kasra then the hamza sits below the 'alif'.
When a hamza appears in the middle of a word it can be "seated" with any of the 3 long vowels or it can be written without a "seat". Note that when the hamza is written over the ي, the ي looses its 2 dots and looks like ئ. It can be difficult to predict which short vowel will go with the hamza. It is best to memorize the "seat" as well as the hamza and its short vowel when memorizing the word. See examples below.
A hamza appearing at the end of a word does not have a "seat" and sits on the line all by itself. See the examples below.