Particles belong to the group of Auxiliary words. There eight classes of particles in Russian language.

1) Imperative particles: пусть — let
Пусть всегда в вашем доме будет счастье! Let there always be happiness in your home! давай — let us, let's
Давай познакомимся. Let's get acquainted.

2) The particle бы:
На вашем месте я бы поехала в Москву. If I were you, I would go to Moscow.

3) Interrogative particle:
ли — if, whether (it is used to express doubt)
Читал ли ты Пушкина ?
Have you read Pushkin?
ли — if, whether (it is used to introduce indirect speech)
Я спросила, читал ли он Пушкина.
I asked if he had ever read Pushkin.

4) Interrogative — emphasizing particles:
неужели — really
Неужели он уехал? Has he really left?
разве — Is (it) ...? Does (it) ...? Разве она русская? Is she really Russian?
Emphatic particles: уже — already, даже — even, ещё — yet.

5) Particles: Как! — How! Ну! — Come on!

6) The particles of agreement:
да — yes; так — yes, so; конечно — certainly; хорошо — well, fine, OK.

7) The particles of rejection: нет — no, не — not, ни — not.

8) The particles used in negative and indefinite pronouns:
ни (никто — nobody) не (некто — someone) кое- (кое-что — something) -то (где-то — somewhere) -либо (кто-либо — anyone) -нибудь (что-нибудь — anything)
Note: Pronouns with -то are used in the present and past tenses. Pronouns with -нибудь, -либо are used in the future tense.