Why is it "j'habite" and not "je habite"?

Question

From my understanding, french does not put two vowel together and will use "j'", "d'", "l'", etc. if there is a vowel as the first letter. I also know that "h" is silent and also uses "j'","d'","l'". etc. 
I would like to know why and if there other letters that follow this rule. Thank you very much in advance.

Cécile Janty-Davies · Accepted Answer

Bonjour Muskaan, 
You are correct in saying that the -h of 'habiter' is silent (mute), which means that you act as if it weren't there at all, and you can liaise  or use an elision as in the case of a clash of vowels.
If the -h has been an -h aspirate, as in the case of a verb like haïr (to hate), you would indeed say -
Je hais mes voisins = I hate my neighbours
Let's have a look at some examples of aspirated verbs and nouns to use the article le -

J'hésite à quitter mes parents = I hesitate to leave my parents
Ils m'hébergent dans l'Hôtel de Paris = They are putting me up in the Hôtel de Paris
Ça m'horripile de le voir comme ça = It exasperates me to see him like this
Le quartier où j'habite est horrible = The district where I live is horrible 
C'est l'heure du déjeuner = It's time for lunch 
L'horloge de la mairie ne marche plus = The town hall clock doesn't work anymore.

Le prix des crèmes hydratantes est hallucinant = The price of moisturising creams is outrageous
In this last example, you would liaise the -s or crèmes with ydratantes and the -t of est with allucinant as if the -h's weren't there at all.
Hope this helps!