Esperanto/Grammar Rules

Esperanto is a constructed language intended to be used for neutral international communication. Esperanto is spoken around the world and has about 2 million speakers. There are 16 basic rules of Esperanto grammar, established by its founder, L.L. Zamenhof:

There is no indefinite article (English a, an); there is only a definite article la, alike for all genders, cases and numbers (English the). The use of the article is as in other languages. People for whom use of the article offers difficulties (e.g. speakers of Russian, Chinese, etc.) may at first elect not to use it at all.
Nouns have the ending -o. To form the plural, add the ending -j. There are only two cases: nominative and accusative; the latter can be obtained from the nominative by adding the ending -n. The other cases are expressed with the aid of prepositions (genitive by de (English of), dative by al (English to), ablative by per (English by means of) or other prepositions, according to meaning).
Adjectives end in -a. Cases and numbers are as for nouns. The comparative is made with the word pli (English more), the superlative with plej (English most); for the comparative the conjunction ol (English than) is used.
The basic numerals (not declined) are: unu, du, tri, kvar, kvin, ses, sep, ok, naŭ, dek, cent, mil (English one, two, three, four, five, six, seven, eight, nine, ten, hundred, thousand). Tens and hundreds are formed by simple juxtaposition of the numerals. To show ordinal numbers we add the adjective ending; for multiples, the suffix -obl; for fractions (actually, reciprocals), -on; for collectives, -op; for divisionals, the word (particle) po. Noun and adverb numerals can also be used.
Personal pronouns: mi, vi, li, ŝi, ĝi (for an object or animal), si, ni, vi, ili, oni (English I, you, he, she, it, oneself, we, you, they, they-one-people); the possessive pronouns are formed by addition of the adjective ending. Declension is as for nouns.
The verb does not change for person or number. Forms of the verb: present time takes the ending -as; past time, -is; future time, -os; conditional mood, -us; command mood, -u; infinitive mood, -i. Participles (with adjectival or adverbial meaning): present active, -ant; past active, -int; future active, -ont; present passive, -at; past passive, -it; future passive, -ot. All forms of the passive are formed with the aid of the corresponding form of the verb esti (English to be) and the passive participle of the required verb; the preposition with the passive is de (English by).
Adverbs can be formed from adjectives by changing the -a ending to an -e ending (like English -ly).
All prepositions take the nominative.
Every word is read as it is written.
The accent always falls on the next-to-last syllable (vowel).
Compound words are formed by simple juxtaposition of words (the main word stands at the end); the grammatical endings are also viewed as independent words.
When another negative word is present, the word ne (English no, not) is omitted.
To show direction, words take the accusative ending.
Every preposition has a definite and permanent meaning, but if we have to use a preposition and the direct meaning doesn't tell us what preposition we should take, then we use the preposition je, which has no independent meaning. Instead of je the accusative without a preposition may be used.
The so-called foreign words, i.e. those taken by the majority of languages from one source, are used in Esperanto without change, taking on only the orthography of this language; but for different words from a single root it is better to use without change only the basic word, and form the rest from this latter according to the rules of Esperanto.
The final vowel of the noun and the article may be dropped and replaced by an apostrophe (without effect on stress).