
all
Refers to the entirety of a countable set; every individual person or thing in a group.
Alle meine Freunde kommen zu meiner Geburtstagsparty.
All my friends are coming to my birthday party.
Loading your saved state.

Refers to the entirety of a countable set; every individual person or thing in a group.
Alle meine Freunde kommen zu meiner Geburtstagsparty.
All my friends are coming to my birthday party.

everything
Used as a pronoun ('alles') to refer to 'every thing' or 'the entirety of something'.
Ich habe alles für den Urlaub eingepackt.
I packed everything for the vacation.

Refers to the entirety of an uncountable amount.
All sein Mut verließ ihn in diesem Moment.
All his courage left him in that moment.

above all / especially
A fixed expression that means 'especially' or 'mainly' and highlights something.
Ich mag Sport, vor allem Fußball.
I like sports, especially soccer.

all gone
Colloquial for 'used up', 'empty', or 'finished'.
Mist, die Milch ist schon wieder all.
Darn, the milk is all gone again.
The ending of `all-` depends on whether an article follows. Without an article, `all-` takes the article ending. If a definite article or possessive pronoun follows, `all` often remains undeclined.
Alle Kinder spielen im Garten.
All children are playing in the garden.
The form `alle` with an ending is used for countable plural nouns. The undeclined form `all` often stands before uncountable singular nouns, usually together with a possessive pronoun.
Alle Stühle in diesem Raum sind besetzt.
All the chairs in this room are occupied.
As a pronoun, the form `alles` (everything) is used and means 'every thing' or 'the entirety'. It is treated like a neuter singular noun and often stands alone as the subject or object.
Ist alles bereit für die Abreise?
Is everything ready for departure?
The phrase `vor allem` (above all / especially) is a fixed combination and means 'especially' or 'mainly'. It is used to particularly emphasize one part of a group or one aspect.
Ich esse gerne Obst, vor allem Äpfel und Bananen.
I like eating fruit, especially apples and bananas.
The meaning 'empty' or 'finished' is colloquial and especially common in southern and western Germany. This meaning is not used in standard language.
Kannst du neue Milch kaufen? Diese hier ist all.
Can you buy new milk? This one is all gone.
whole / quite
All and ganz can both refer to a complete amount. All emphasizes the entire amount and comes before the article, while ganz views the content referred to more as a complete unit and comes after the article. In many situations, both are possible, but the perspective is different.

Sie verteilte all das Wasser aus der Flasche auf die Becher.
She distributed all the water from the bottle among the cups.
Sie goss das ganze Wasser aus der Flasche auf einmal in den Topf.
She poured the whole amount of water from the bottle into the pot all at once.