Different types of particles in English

Articles, infinitival, prepositional, and adverbial particles

* The definite article the (the indefinite article a or an cannot really be classed as uninflected as in the plural it is not used)
* the infinitive to, as in to walk
* prepositions, such as over as in I went over the hill
* adverbs, such as even as in even the youngest of them; or phrasal verbs, such as put off as in we put it off too long

[edit] Interjections, sentence connectors, and conjunctions

Sentence connectors, tags or tag questions (also called sentence-finals), and conjunctions connect to what has been said in a previous clause or sentence. These three types of grammatical particles (similarly to modal particles in some other languages) also reflect the speaker's mood and attitude toward what has come before in the conversation, or is likely to follow later. Because of their similar functions,Interjections, sentence connectors, and conjunctions should be grouped together:

Interjections

* ah
* alas
* farewell
* goodbye
* hello
* hi
* hmm
* hum
* meh
* no
* oh
* ouch
* wow
* yes
* zzzzzzzzz (as in a cartoon for someone sleeping, one of the few non-vocal interjections)

The list of interjections is probably never-ending as it belongs to the open class word category and is subject to new creations at all times.

Sentence connectors

* so (as in So what)
* well (as in Well, we can’t help that)
* still (as in Still, it could have been a lot worse)
* yet (as in I am older now, yet I still enjoy some of the things I used to do)
* as
* also
* however
* nevertheless
* otherwise
* anyway
* then
* too (as in that, too, has been said in the past}

Tags or tag questions (sentence-finals)

* "...didn't they?"; "...wasn't it?"; "...shouldn't it?", etc.

Conjunctions

* and
* or
* nor
* but
* while (while it is true that all line repairs are undertaken on Sundays, not all trains should be assumed to be late)
* although/though
* for (as in she could not see the film, for she was too young
* because
* unless
* since (as in since you asked, I will tell you)
http://en.wikipedia.org/wiki/Grammatical_particle