Esperanto Quick Reference

Based on Grammar reference at lernu.net and other sources.  May be inaccurate - I'm just a beginner.

Adverbs

Adverbs are words that indicate manner, place, time or quantity; for example:

ankoraŭ - still, yet	almenaŭ - at least	apenaŭ - barely, only just, hardly, scarcely	baldaŭ - soon	preskaŭ - almost
eĉ - even	jam - already	jen - behold, here is, here are, look, there,	ĵus - just, just now	morgaŭ - tomorrow
hodiaŭ - today	hieraŭ - yesterday	nun - now	nur - only	plu - more, on, else, further
tre - very	tro - too, too much	tuj - at once, right now, immediately	for - away

It's also possible to create adverbs from other words by using the -e ending. The meaning of the base word determines whether it becomes a manner, place, time or quantity adverb.
rapida - quick | rapide - quickly (adverb of manner)
skribi - write | skribe - in writing (adverb of manner)
hejmo - home | hejme - at home (place adverb)
nokto - night | nokte - at night (time adverb)
multaj - many | multe - much (quantity adverb)

Adverbs have a more diverse set of acceptable meanings than in English.  For example, you would not say "morningly", but you can say "matene" (in the morning).

Affixes

The affixes (prefixes and suffixes) are very important in Esperanto. There are 10 prefixes and 32 suffixes.

Prefixes

bo-		related by marriage		patro	-	father		bopatro	-	father-in-law
dis-		in several directions		doni	-	to give		disdoni	-	to distribute
ek-		(suddenly) begin		vidi	-	to see		ekvidi	-	to glimpse
eks-		no longer		reĝo	-	king		eksreĝo	-	ex-king
fi-		bad (in principle referring to character)		domo	-	house		fidomo	-	house of shame
ge-		the two sexes together		patro	-	father		gepatroj	-	parents
mal-		inverse; opposite		bona	-	good		malbona	-	bad
mis-		not rightly; in error		uzi	-	to use		misuzi	-	to abuse
pra-		a very long time ago or (when talking about descendents) future		tempo	-	time		pratempo	-	ancient times
re-		again, another time; inverse direction		veni	-	to come		reveni	-	to return

Suffixes

-aĉ-		bad (in principle referring to quality)		domo	-	house		domaĉo	-	hovel
-ad-		continuous or repeated action		kanti	-	to sing		kantado	-	singing
-aĵ-		something concrete, specific		alta	-	high		altaĵo	-	a height (highland, etc.)
-an-		member		Kristo	-	Christ		kristano	-	Christian
-ar-		many taken as a whole		arbo	-	tree		arbaro	-	forest
-ĉj-		forms familiar form of male names (after 2-5 letters of the name)		patro	-	father		paĉjo	-	Dad
-ebl-		can be done		legi	-	to read		legebla	-	legible
-ec-		quality as an abstract idea		rapida	-	fast		rapideco	-	speed
-eg-		very large; very strongly		varma	-	warm		varmega	-	hot
-ej-		place		kuiri	-	cook		kuirejo	-	kitchen
-em-		inclination or tendency		dormi	-	to sleep		dormema	-	sleepy
-end-		must be done		legi	-	to read		legenda	-	must be read
-er-		fragment, one of many similar pieces		sablo	-	sand		sablero	-	grain of sand
-estr-		person who guides, rules, presides		lernejo	-	school		lernejestro	-	principal/head teacher
-et-		very small; very weakly		varma	-	warm		varmeta	-	lukewarm
-id-		offspring		hundo	-	dog		hundido	-	puppy
-ig-		cause something to be		labori	-	to work		laborigi	-	to put someone to work
-iĝ-		become		ruĝa	-	red		ruĝiĝi	-	to blush
-il-		instrument, tool		tranĉi	-	to cut		tranĉilo	-	knife
-in-		indicates female sex		knabo	-	boy		knabino	-	girl
-ind-		good to do, worthy of		legi	-	to read		leginda	-	worth reading
-ing-		a holder into which something is inserted		glavo	-	sword		glavingo	-	scabbard
-ism-		way of thought, belief system		kristano	-	Christian		kristanismo	-	Christianity
-ist-		practitioner of a profession, continued hobby or way of thinking		labori	-	to work		laboristo	-	worker
-nj-		forms familiar form of female names (after 2-5 letters of the name)		patrino	-	mother		panjo	-	Mom
-obl-		multiplication; times		du	-	two		duoblo	-	double
-on-		fraction		du	-	two		duono	-	half
-op-		group of		du	-	two		duope	-	in a pair
-uj-		container		mono	-	money		monujo	-	wallet, change purse
-ul-		person		juna	-	young		junulo	-	a youth
-um-		indefinite relation		komuna	-	common		komunumo	-	community

Several prefixes and suffixes can be used together.
patro - father = > bogepatroj - in-laws (shouldn't it be parents-in-law?)
labori - to work = > mallaborema - lazy

Several prefixes and suffixes can be used on their own.
ilo - tool
ekas - begins

Correlatives

Question and answer words are linked in a separate system. It consists of five beginnings and nine endings which can be combined in many ways.

Beginning Short clarification ki- [what] ti- [that] i- [some] ĉi- [every] neni- [no]

Ending Short clarification -o thing -u one, or person -a kind of, sort of -el manner, in ... way -e place -am time -om quantity (amount) -al reason, for ... reason -es one's, person's

kio - what, what thing	tio - that, that thing	io - something, anything	ĉio - everything, all things	nenio - nothing
kiu - who, which one	tiu - that person, that one	iu - someone, somebody	ĉiu - everyone, everybody	neniu - no one, nobody
kia - what kind of, what (a)	tia - that kind of, such a	ia - some kind of, any kind of	ĉia - every kind of, all kinds of	nenia - no kind of
kiel - how, in what way	tiel - that way, thus, like that, so	iel - somehow, in some way	ĉiel - in every way	neniel - in no way
kie - where, in what place	tie - there, in that place	ie - somewhere, anywhere, in some place	ĉie - everywhere, in every place	nenie - nowhere, in no place
kiam - when, at what time	tiam - then, at that time	iam - sometime, anytime, ever	ĉiam - always, at all times	neniam - never, at no time, not ever
kiom - how much, how many, what quantity	tiom - so much, as many, that quantity	iom - some, some quantity	ĉiom - the whole quantity, all of it	neniom - not a bit, none, no quantity
kial - why	tial - for that reason	ial - for some reason	ĉial - for every reason	nenial - for no reason
kies - whose	ties - that one's	ies - someone's	ĉies - everyone's	nenies - no one's

Ĉi

The word ĉi expresses closeness and is used with the ti- and ĉi-vortoj, either before or after them.
tie ĉi / ĉi tie - here
tiu ĉi / ĉi tiu - this one
ĉio ĉi / ĉi ĉio - all of this

Ajn

The word ajn means '...ever':
kiam ajn - whenever
kiu ajn - whoever

Relative words

The ki-words are also used as relative (interrelational) words.
Tio, kion li diris, estas bona. - that, which he said is good
La knabino, kiu staras tie. - the girl, which stands there
Ĝi estas granda kiel domo. - it is large like a house

Prepositions

Prepositions may be required in some places where they are not required in English.  I've not yet determined the rules.

Preposition		Translation		Example
al		to		Mi iras al vi. - I'm going to you.
anstataŭ		instead of		Mi iras anstataŭ vi. - I'm going instead of you.
antaŭ		in front of, before		Mi iras antaŭ vi. - I'm going in front of/before you.
apud		near, beside		Mi iras apud vi. - I'm going near you.
ĉe		at, near, with		Mi sidas ĉe komputilo. - I'm sitting at a computer.
ĉirkaŭ		around		Mi iras ĉirkaŭ vi. - I'm going around you.
da		of (quantities)		Ni havis multe da gastoj. - We had a lot of guests.
de		of, from		Mi iras de la domo. - I'm going from the house.
dum		while, during, time of		Ni iris dum tri minutoj. - We went for three minutes.
ekster		outside (of)		Mi iras ekster la domo. - I'm going outside the house.
el		out of, from within		Mi iras el la domo. - I'm going from the house.
en		in		Mi iras en la domo. - I'm going in the house.
ĝis		until		Mi iras ĝis la domo. - I'm going until [I reach] the house.
inter		among, between		Mi iras inter la domoj. - I'm going between the houses.
je		(indefinite meaning)		Li kredas je Dio. - he believes in God
kontraŭ		against		Mi iras kontraŭ via volo. - I'm going against your wish.
krom		except		Ĉiuj krom mi iris. - Everyone, except me, went.
kun		with, together		Mi iras kun vi. - I'm going with you.
laŭ		according to		Mi iras laŭ la vojo. - I'm going along (according to) the way.
malgraŭ		in spite of, despite		Mi iras malgraŭ la pluvo. - I'm going in spite of the rain.
per		with, using, by means of		Mi vojaĝas per trajno. - I'm traveling by train.
por		for		Mi eniras por manĝi. - I'm entering to eat.
po		at the rate of, per		Po du eŭroj por persono. - Two euros per person.
post		after (time)		Mi iras post vi. - I'm going after you.
preter		past, beyond		Mi iras preter vi. - I walk past you.
pri		about, concerning		Mi pensas pri vi. - I'm thinking about you.
pro		for (because of)		Mi eniras pro la pluvo. - I'm entering because of the rain.
sen		without		Mi iras sen vi. - I'm going without you.
sub		under		Mi iras sub la domo. - I'm going under the house.
super		above		Mi estas super vi. - I'm above you.
sur		on (position)		Mi estas sur la domo. - I am on the house.
tra		through		Mi iras tra la domo. - I'm going through the house.
trans		across		Mi iras trans la strato. - I'm going across the street.

De is used in many ways, for expressing many things, like moving away, origin, cause, time or a property (respectively).
Mi venas de la urbo. - I come from the city.
Mi ricevis kison de vi. - I received a kiss from you.
Mi ridas de ĝojo. - I laugh from joy.
De nun mi amas vin. - From now on, I love you.
Glaso de biero. - Glass of beer (a glass, which contains beer)

Da is used between a quantity word and the measurement you're expressing.
kilogramo da rizo - kilogram of rice
du litroj da lakto - two liters of milk
glaso da biero - glass of beer (a glass-sized quantity of beer)
multe da bananoj

When no other preposition works, you can use the indefinite preposition je.
Li kredas je Dio. - he believes in God.

Another usual use of je is in time expressions:
je la tria horo - at the third hour (i.e. at three o'clock) 

Direction by -n

Typically, after prepositions you should use the basic word form without -n.
pri la knabo - about the boy
en la domoj - in the houses
al la urbo - to the city

But after prepositions which indicate directions, you need to use -n to show motion to that location.
Hundo saltas sur la tablo. - A dog jumps on the table. (i.e. a dog jumps while on the table)
Hundo saltas sur la tablon. - A dog jumps onto the table.
Mi iras en la domo. - I go in the house. (i.e. I go while in the house)
Mi iras en la domon. - I go into the house.

-n works the same way after adverbs which indicate location.
hejme - at home | hejmen - [to] home
urbe - in the city | urben - to the city
kie - where | kien - to where
tie - there | tien - to there

See also

• Lernu! http://www.lernu.net/
• Free esperanto course: http://pacujo.net/esperanto/course/
• Another one: http://anaproy.homeip.net/esperantocourse/