Weak Ties

In sociology and social network analysis, an interpersonal tie is a connection between two or more people.

So a friendship is a type of interpersonal tie, as is someone following you on Instagram. Periodically seeing someone while passing them in the hallway at school is a type of interpersonal tie, as is marrying someone, going to someone's wedding, or working at the same office as someone and chatting with them about the weather in the break room maybe once a week.

Generally these connections are segmented into three categories: weak, strong, and absent or invisible ties.