zugänglich
accessible
Designed or situated in such a way that one can easily reach or enter a place.
Der neue Bahnhof ist für Rollstuhlfahrer barrierefrei zugänglich.
The new train station is fully accessible for wheelchair users.

accessible
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accessible
Designed or situated in such a way that one can easily reach or enter a place.
Der neue Bahnhof ist für Rollstuhlfahrer barrierefrei zugänglich.
The new train station is fully accessible for wheelchair users.

The word consists of 'zu' and 'gänglich', which comes from the verb 'gehen' (to go), through the old word 'Gang' (way, passage). Something that is 'zugänglich' (accessible) is therefore literally something you can 'go to'.
Der Park ist für die Öffentlichkeit frei zugänglich.
The park is freely accessible to the public.
'Zugänglich' (accessible) is often used with the preposition 'für' + accusative. This specifies for which group or purpose something is accessible.
Diese Ausstellung ist auch für Kinder sehr gut zugänglich.
This exhibition is also very accessible for children.
The context reveals the meaning: If it is about a place (e.g., a building, park), spatial accessibility is meant. If it is about knowledge or art (e.g., a book, topic), understandability is meant. If it refers to a person, it means their open character.
Der Strand ist nur bei Ebbe zugänglich.
The beach is only accessible at low tide.
In the meaning of 'verständlich' (understandable), the construction 'etwas zugänglich machen' (to make something accessible) is often used. It means to explain a complex topic in a simple way.
Der Professor hat die Fähigkeit, komplizierte Theorien für Studenten zugänglich zu machen.
The professor has the ability to make complicated theories accessible to students.
open
'offen' and 'zugänglich' can both mean that something or someone is not closed off or unwelcoming. 'offen' is more general: a place can be open to everyone, and a person can be open to new ideas. 'zugänglich' fits especially well when a place is easy to reach or enter. For people, 'zugänglich' means that they are approachable and friendly in contact. Learners may confuse the words because both sound positive when describing people. As a guide: 'offen' emphasizes the attitude more, while 'zugänglich' emphasizes easy accessibility or easy contact.

Der kleine See ist nur über einen schmalen Weg zugänglich.
The small lake is accessible only via a narrow path.
Nach dem Gespräch ist sie offener für den Vorschlag der Trainerin.
After the conversation, she is more open to the trainer's suggestion.