Learn Hardcore German: Der Gartenstuhl steht neben dem Tisch im Garten. - The garden chair stands next to the table in the garden.

In Der Gartenstuhl steht neben dem Tisch im Garten, we are asking who/what is standing? → der Gartenstuhl.
Subjects answer who/what? and take nominative, so der is correct.

Why is steht used instead of ist? In English I would say The garden chair is next to the table.

German often prefers posture verbs instead of a simple to be for things and people in a location:

stehen – to stand / to be standing
liegen – to lie / to be lying
sitzen – to sit / to be sitting
hängen – to hang / to be hanging

So Der Gartenstuhl steht neben dem Tisch literally means:
The garden chair stands next to the table, which is also how German naturally says The garden chair is (standing) next to the table.

You can say Der Gartenstuhl ist neben dem Tisch, but it sounds more neutral and less idiomatic. Using steht gives a more natural, vivid description of how the chair is positioned.

Why is it neben dem Tisch and not neben den Tisch?

Neben is a two-way preposition (Wechselpräposition). It can take dative or accusative:

Dative → location (no movement): Where is something?
Accusative → direction (movement): Where is something going / being put?

In the sentence, the chair is simply located there:

Der Gartenstuhl steht neben dem Tisch.
→ Where does it stand? Next to the table.
→ dative: dem Tisch

If it were movement towards the position, you’d say:

Ich stelle den Gartenstuhl neben den Tisch.
→ I am putting the chair next to the table.
→ accusative: den Tisch

Why is it dem Tisch and not der Tisch?

Der Tisch is nominative masculine.
After neben (with static location), we need dative:

Masculine singular definite article:

Nominative: der Tisch
Accusative: den Tisch
Dative: dem Tisch

Because neben here expresses location (no movement), it requires dative, so dem Tisch is correct: neben dem Tisch.

What exactly does im Garten mean? Is im one word?

Im is a contraction of in dem:

in = in
dem = dative masculine/neuter singular article
in dem Garten → im Garten

So im Garten literally means in the garden.

Again, in is a two-way preposition:

With dative → location: im Garten (in the garden)
With accusative → direction: in den Garten (into the garden)

Why does in also take the dative case here?

As with neben, in is a two-way preposition:

Dative → location (where something is):
Der Gartenstuhl steht im Garten.
→ The garden chair is (standing) in the garden.
Accusative → direction/movement (where something goes):
Ich trage den Gartenstuhl in den Garten.
→ I carry the garden chair into the garden.

In your sentence, the garden chair is already there; it is a static location, so dative is used: im (in dem) Garten.

Why is the word order neben dem Tisch im Garten and not im Garten neben dem Tisch?

Both orders are grammatically correct:

Der Gartenstuhl steht neben dem Tisch im Garten.
Der Gartenstuhl steht im Garten neben dem Tisch.

Typical tendencies:

German often goes from more specific to more general in location:
- neben dem Tisch (very specific spot)
- im Garten (broader location)
Speakers also choose order based on focus:
- If you’re contrasting where exactly near the table, you might stress neben dem Tisch.
- If you want to emphasize that it’s the garden (not the house), you might say im Garten earlier.

So it’s a matter of style and emphasis, not a strict rule.

Why is Gartenstuhl written as one word instead of Garten Stuhl?

German loves compound nouns. When two nouns belong closely together in meaning, they are usually joined into one word:

Garten
- Stuhl → Gartenstuhl (garden chair)
Garten
- Haus → Gartenhaus (garden shed)
Kinder
- Zimmer → Kinderzimmer (children’s room)

Generally, German does not write a space between such parts. English might use a space (garden chair), a hyphen (garden-chair), or one word (notebook); German usually prefers one long noun.

Why is it Der Gartenstuhl steht and not something like Der Gartenstuhl ist stehend?

German almost never uses forms like ist stehend, ist liegend, etc. for normal location descriptions.

Instead:

Use sein (ist) with an adjective:
Der Gartenstuhl ist alt. (The garden chair is old.)
Use a posture verb with a prepositional phrase for location:
Der Gartenstuhl steht neben dem Tisch.
(The garden chair is standing next to the table.)

So Der Gartenstuhl steht … is the standard, idiomatic way to say The garden chair is (in a standing position) …

How would this sentence look in the plural?

Singular:

Der Gartenstuhl steht neben dem Tisch im Garten.
→ The garden chair stands / is standing next to the table in the garden.

Plural:

Die Gartenstühle stehen neben dem Tisch im Garten.
→ The garden chairs stand / are standing next to the table in the garden.

Changes:

der Gartenstuhl → die Gartenstühle (plural noun and plural article)
steht (3rd person singular) → stehen (3rd person plural)
dem Tisch, im Garten stay the same (dative singular forms, unchanged).

Why are Gartenstuhl, Tisch, and Garten all masculine? Is there a logic?

Their genders are:

der Gartenstuhl – masculine
der Tisch – masculine
der Garten – masculine

Unfortunately, grammatical gender in German is largely arbitrary and must usually be memorized with the noun. There are some patterns (e.g. many nouns ending in -en are masculine), but they are not 100% reliable.

Good habits:

Always learn nouns with their article: der Gartenstuhl, der Tisch, der Garten.
Or learn with a color or symbol for gender.

So there is no deep logical reason; it is mainly vocabulary you need to remember.

What is the difference between neben dem Tisch and bei dem Tisch?

Both can often be translated as near the table, but they have different nuances:

neben dem Tisch
- literally: next to the table, at the side of it
- suggests a very specific lateral position, often quite close
bei dem Tisch (often contracted: beim Tisch)
- broader meaning: by the table, at the table, near the table
- can describe general vicinity or association, not just directly next to its side

In your sentence, neben dem Tisch fits best because a chair is normally placed directly next to (alongside) a table.