The Grammar of Esperanto

At the time of the writing of this article, major web browsers still do not fully support Unicode. There are 6 letters in Esperanto that are not normally part of English native character sets. We're going to improvise them as follows:

"C^" will represent the Esperanto letter C marked with a circumflex.
"G^" will represent the Esperanto letter G marked with a circumflex.
"H^" will represent the Esperanto letter H marked with a circumflex.
"J^" will represent the Esperanto letter J marked with a circumflex.
"S^" will represent the Esperanto letter S marked with a circumflex.
"U^" will represent the the Esperanto letter U marked with a breve.

The 16 simple rules to say anything in Esperanto:

1. Articles

Esperanto has no "a" or "an". Esperanto has only the definite article "la", which is equivalent to "the" in English.
     "hundo"                            "dog, a dog"
     "la hundo"                         "the dog"
     "leono"                            "lion, a lion"

2. Nouns

Nouns are either subjects or direct objects. Nouns which are subjects end in "-o". Nouns which are direct objects end in "-on". Their plurals are formed with the "-oj" or "-ojn" suffix respectively. If a noun is neither a subject nor a direct object, use a prepositional phrase.
     "La leono mordas."                         "The lion bites."
     "La leonoj mordas."                        "The lions bite."
     "La leono mordas hundon."                  "The lion bites a dog."
     "La leono mordas hundojn."                 "The lion bites dogs."
     "La hundoj mordas leonojn en la g^angalo." "The dogs bite lions in the jungle."

3. Adjectives

Adjectives end in "-a". For clarity, the case and number of an adjective always match the noun it describes. Depending on the noun, then, an adjective could end in "-a", "-an", "-aj", or "-ajn".
     "la bruna hundo"                       "the brown dog"
     "la brunaj hundoj"                     "the brown dogs"
     "La leono mordas la brunajn hundojn."  "The lion bites the brown dogs."
Comparisons are formed with the word "pli" for "more", "plej" for "most", and "ol" for "than".
     "la bruna hundo"                         "the brown dog"
     "la pli brunaj hundoj"                   "the browner dogs"
     "La hundo estas pli bruna ol la leono."  "The dog is browner than the lion."
     "la plej bruna hundo"                    "the brownest dog"

4. Numbers

The basic numerical elements are:
     "unu"   "one"               "sep"   "seven"
     "du"    "two"               "ok"    "eight"
     "tri"   "three"             "nau^"  "nine"
     "kvar"  "four"              "dek"   "ten"
     "kvin"  "five"              "cent"  "hundred"
     "ses"   "six"               "mil"   "thousand"
Compound numbers are formed by prefacing each decimal position with a multiplier. The ordinal is formed by hyphenating all decimal positions and adding the "-a" suffix.
     "dek unu"                   "11"
     "dek-unua"                  "11th"
     "dudek tri"                 "23"
     "mil nau^cent okdek kvar"    "1984"

5. Pronouns

The personal pronouns are:
     "mi" "me"              "s^i" "she"                "ni"  "we"
     "vi" "you"             "li"  "he"                 "ili" "they"
                            "g^i" "it"
The possessive pronoun is formed by adding an "-a".
     "mia"                             "my"
     "mia hundo"                       "my dog"
     "miaj hundoj"                     "my dogs"
     "La leono mordis miajn hundojn!"  "The lion bit my dogs!"

6. Verbs

Verbs undergo no change with regard to person or number. The infinitive form ends in "-i". Tenses are indicated by replacing the "-i" suffix.
    Suffix     Tense                    Example
    -------  ----------    ---------------------------------------
     "-i"    infinitve     "mordi"            "to bite"
     "-as"   present       "Mi mordas."       "I bite."
     "-is"   past          "Mi mordis lin."   "I bit him."
     "-os"   future        "Mi mordos lin."   "I will bite him."
     "-us"   conditional   "Mi mordus lin."   "I would bite him."
     "-u"    imperative    "Mordu lin!"       "Bite him!"
participle:Participles (adjectives created from verbs) can be formed with the "-nta" or "-ta" suffixes.
    Suffix       Participle        Example
   --------  -----------------  ----------------------------------------------
     "-ant"   active present     "la falanta stelo"    "the falling star"
     "-int"   active preterite   "la falinta soldato"  "the fallen soldier"
     "-ont"   active future      "knabo estas falonta" "a boy is about to fall"
     "-at"    passive present    "s^telata biero"      "a beer being stolen"
     "-it"    passive preterite  "s^telita biero"      "a stolen beer"
     "-ot"    passive future     "s^telota biero"      "a beer about to be stolen"

7. Adverbs

Adverbs always end in "-e". Use "pli", "ol" and "plej" as you do for adjectives.
     "rapida viro"                              "a quick man"
     "La viro kuras rapide."                    "The man runs quickly."
     "La hundo kuras pli rapide ol la viro."    "The dog runs more quickly than the man."
     "La leono kuras plej rapide."              "The lion runs the most quickly."

8. Prepositional Phrases

In a prepositional phrase, the object of the preposition ends in "-o", not "-on".
     "La hundoj mordas la leonon kum siaj dentoj." 
     "The dogs bite the lion with their teeth."

9. Pronounciation

Every word is pronounced literally as it is spelled. No exceptions.

10. Syllable Accent

The accent is always on the second to last syllable. No exceptions.
     "RAdo"                       "a wheel"
     "familIo"                    "a family"
     "plenkresKULo"               "an adult"

11. Compound Words

Compound words are formed by combining words together, with the most important word at the end. If a vowel is needed to make the word pronounceable, use an "-o-".
     "c^ambro"                    "a room"
     "mang^i"                     "to eat"
     "mang^oc^ambro"              "a dining room"

The word "room" comes last, because a dining room is a room, not something you eat.

12. Double Negatives

Double negatives are not used in Esperanto. Do not use "no" with a word that indicates the negative, such as "nothing" or "never".
     "ne"                              "no"
     "nenio"                           "nothing"
     "Ne mi havas la hundon."          "I do not have the dog."
     "Mi havas nenion."                "I have nothing"
     "Ne mi havas nenion!"             INCORRECT! This is a double negative!

13. Direction and Approach

Giving the object of a preposition the "-n" ending can indicate motion towards the object.
     "Neniom monoj saltas sur la lito."   "No more monkeys jumping on the bed."
     "La infano saltas sur la liton."     "The child jumps onto the bed."   

14. Prepositions (II)

If no preposition really fits the relation you're trying to express, use the generic preposition "je". You could also add the "-n" suffix to the noun and forego the preposition altogether.

15. New Words

When a word is imported from a foreign language into Esperanto, transliterate the root word and apply the appropriate Esperanto suffix(es).
     "chocolat-"        "c^okolad-"
     "chocolatey"       "c^okolada"

16. Poetic License

The final vowel of a noun or the article "la" may be dropped and replaced with an apostrophe.
     "la hundo"         "the dog"
     "l' hund'"         "the dog"