This is the 2400th most frequent German word.
old
The German word "alt" means "old" in English.
In this sentence, 'alt' (old) is used as an adjective to describe a person (Mann), and it is inflected (alte) to agree with the gender (masculine) and number (singular) of the noun.
Der alte Mann erzählte uns viele Geschichten.
The old man told us many stories.
Here, 'alt' is used predicatively to describe the subject (Technik) without direct inflection.
Diese Technik ist alt, aber effizient.
This technique is old, but efficient.
Here, 'alt' (old) is used as an adjective to describe the book (noun) and is inflected (alte) to agree with the gender (neuter) and case (nominative) of the noun it modifies.