Rule 1
The alphabet
Esperanto uses 28 letters. There is no Q, W, X, or Y. Six letters carry a small mark: ĉ, ĝ, ĥ, ĵ, ŝ, ŭ. Each letter has one sound. You read every word exactly as it is written.
ĉambro, ĝojo, ŝipo
room, joy, ship
Esperanto grammar
Zamenhof published these sixteen rules in 1887. They are the whole formal grammar. Learn them once; they do not grow a secret list of exceptions.
Rule 2
Nouns end in -o
Every noun ends in -o. Add -j for the plural: libro / libroj. Add -n when the noun is the direct object: Mi legas libron. (I read a book.)
hundo, hundoj, hundon
dog, dogs, dog as object
Rule 3
Adjectives end in -a
Adjectives end in -a and follow the noun’s number and case: bona libro, bonaj libroj, bonan libron. Word order is free because the endings carry the meaning.
granda urbo / grandajn urbojn
a big city / big cities (object)
Rule 4
Numbers do not change
Cardinal numbers are invariable: unu, du, tri, kvar, kvin, ses, sep, ok, naŭ, dek. You do not add -j or -n to them. Ordinals add -a: unua (first), dua (second).
du bonaj libroj · la unua tago
two good books · the first day
Rule 5
Pronouns
mi (I), vi (you), li (he), ŝi (she), ĝi (it), ni (we), ili (they), oni (one/people), si (himself/herself). Possessives add -a: mia libro (my book).
Mia amiko vidas ŝin.
My friend sees her.
Li vidas sin. Li vidas lin.
He sees himself. He sees him (another man). si is always the same person as the subject; li is someone else.
Rule 6
Verbs: one form for everyone
Verbs do not change for person or number. Infinitive -i (lerni), present -as (lernas), past -is (lernis), future -os (lernos), conditional -us (lernus), command -u (lernu). Active participles: -anta, -inta, -onta.
Mi lernas. Ili lernis. Ni lernos.
I learn. They learned. We will learn.
Mi volas lerni. Ŝi povas veni.
I want to learn. She can come. After another verb, keep the infinitive -i.
Rule 7
Adverbs end in -e
Turn an adjective into an adverb with -e: bona / bone (well), rapida / rapide (quickly). Comparison: pli bone (better), plej bone (best).
Ŝi parolas bone kaj rapide.
She speaks well and quickly.
Rule 8
Prepositions take the nominative
After a preposition, use the basic form without -n: en la urbo (in the city), kun amiko (with a friend). Exception: if you show motion toward, you may add -n: en la urbon (into the city).
Mi estas en la urbo. Mi iras en la urbon.
I am in the city. I go into the city.
Rule 9
Every word is read as written
There are no silent letters and no surprise pronunciations. If you can see the word, you can say the word. This is why beginners speak Esperanto on day one.
kaj, tre, hodiaŭ
and, very, today — said exactly as spelled
Rule 10
Stress falls on the second-last syllable
Always stress the syllable before the last: ra-PI-da, es-pe-RAN-to, a-MI-ko. This one rule covers every word.
Esperanto, familio, lerni
es-pe-RAN-to, fa-mi-LI-o, LER-ni
Rule 11
Compound words are built clearly
Put the modifying word first, main word last: vapor·ŝipo (steam-ship), skrib·tablo (writing-table). A hyphen or a vowel can ease the join. You can guess new words from the parts.
lernolibro, noktmezo, bonvena
textbook, midnight, welcome
Rule 12
No double negative needed
One negative word is enough. Mi scias nenion means “I know nothing.” Do not stack ne plus another negative unless you want the meaning to flip.
Neniu venis. Mi ne komprenas.
Nobody came. I do not understand.
Rule 13
The accusative shows direction
Add -n to show movement toward a place, even without a preposition: Mi iras hejmen (I go home). Mi flugas Parizon (I fly to Paris). Location stays without -n: Mi estas hejme.
Ni veturas Londonon. Ni loĝas en Londono.
We travel to London. We live in London. (second often with en)
Rule 14
Each preposition has a clear meaning
al (to), de (from/of), en (in), kun (with), por (for), pri (about), sur (on), sub (under). If no other preposition fits, use je. You may also drop the preposition and use the -n ending.
Mi parolas pri Esperanto kun vi.
I speak about Esperanto with you.
Rule 15
International words stay recognizable
Words shared across Europe and beyond keep a familiar shape, then take Esperanto endings: teatr·o, muzik·o, telefon·o, universitat·o. You already know more Esperanto than you think.
universitato, muziko, telefono
university, music, telephone
Rule 16
The article is always la
There is one definite article: la. It never changes for gender or number: la libro, la libroj, la virino. There is no indefinite article. Libro can mean “a book.”
La suno brilas. Infano ludas.
The sun shines. A child is playing.
Beyond the 16 rules
Table words
Forty-five words from five starts and nine endings. Kellerman introduces them in their grammatical families first, then as one table. Once you see the grid, kiam and ĉiam and neniam are the same ending with three different heads.
Word-building
Esperanto does not ask you to memorise a warehouse of unrelated forms. It stores roots. Affixes are withheld until simple words are familiar — then they multiply what you know. mal- alone cuts the list in half.