以及【yǐjí】

以及 joins nouns and noun phrases: "and", "as well as". It usually goes before the last item of a list whose other items are separated by 、, and it belongs to written Chinese – forms, notices, reports, articles.

It can also join longer phrases, including question phrases that act as nouns, after a comma.

以及 or 和

和 is the everyday "and" between nouns, in speech and writing. 以及 is formal, and suits a list whose items fall into groups, or whose last item is added on after the main ones: 校长、老师以及学生代表 "the head, the teachers, and some student representatives".

Not between adjectives or verbs

Like 和, 以及 doesn't join two adjectives or two predicates about the same subject. Use 又…又 or 既…又.

• × 他很高以及很帅 → 他又高又帅
• × 我们吃饭以及聊天 → 我们一边吃饭一边聊天

及 on its own means the same and is even more compressed; it has its own point.