Learn Hardcore Portuguese (Portugal): Esta cadeira é mais confortável do que o banco da cozinha. - This chair is more comfortable than the kitchen stool.

este / esta → close to the speaker (“this” here)
esse / essa → close to the listener (“that” near you)
aquele / aquela → far from both (“that” over there)
So esta cadeira means “this chair” (the one near me).

Why is the sentence é mais confortável do que and not just é mais confortável que?

The standard comparative of inequality in European Portuguese uses mais … de/da/do que. You always have a preposition de before the second element:

de + o → do
de + a → da
Thus mais confortável do que (“more comfortable than”). In very casual speech you might hear mais confortável que, but the prescriptive form includes do.

What’s happening with the contractions do and da in do banco and da cozinha?

In Portuguese the preposition de (“of/from”) combines with definite articles:

de + o turns into do
de + a turns into da
Hence o banco da cozinha literally means “the bench of the kitchen,” i.e. the kitchen bench.

Why is the adjective confortável placed after the noun cadeira and not before, like in English?

Portuguese normally follows the pattern [noun] + [adjective] for descriptive adjectives. Putting the adjective before the noun can give a poetic or emphatic nuance, but in everyday speech you say cadeira confortável, never confortável cadeira.

Why does é have an accent mark, whereas e (and) doesn’t?

é with an acute accent is the third-person singular present of the verb ser (“to be”). The accent distinguishes it from the conjunction e (“and”), which is always written without an accent.

Do we always need the definite articles a and o before cadeira and banco?

Yes, when talking about specific, concrete objects in European Portuguese, you normally include the definite article:

a cadeira (“the chair”)
o banco (“the bench”)
Omitting them (saying just cadeira or banco) sounds generic or like a title/label, not a particular chair or bench.

What’s the difference between banco and cadeira in Portuguese?

Although both can translate as “seat,” they aren’t interchangeable:

cadeira usually means a chair with a back and often four legs.
banco refers to a bench or stool, commonly without a back, or a built-in kitchen bench.

Could we use tão confortável como instead of mais confortável do que?

You can, but it changes the meaning:

tão confortável como = “as comfortable as” (equality)
mais confortável do que = “more comfortable than” (inequality)
So if you want to say “this chair is just as comfortable as the kitchen bench,” you’d use tão confortável como.