• Almost
The word almost is an adverb. Its meaning is similar to "nearly".
- I almost failed the exam. (but I didn't fail)
- He almost died. (but he didn't die)
- She's almost twenty years old. (she'll be 20 next month)
- He's almost two metres tall. (he's 1m 97cm)
- He was almost dead. (but the doctors managed to save him)
• Almost all
People sometimes get confused with almost all, but it's really very simple. It simply means: almost + all
- Look at the example above: I know almost everyone here.
- That is the same as saying: I know almost all the people here. (nearly all the people)
• Most
As an adjective, most means the "majority", the "largest part", "nearly all of". For example:
- Most cars have four doors.
- Most people would like to be rich.
- I have been to most countries in Europe, but not all.
We also use most as a pronoun, with a similar meaning:
- Most of my friends can speak English.
- I spent most of the $100 you gave me. I've got about $15 left.
- Some people like to make trouble, but most just want a quiet life.