There are different degrees of friendship. Some friends are casual; you may share a couple of interests with them, and you may talk sometimes, but you're not as deep as you could be, and that's just how the friendship is. Other friends you're more close to. You spend time whenever you can, and you've been through it all. You may have had a childhood with them and have experienced ups and downs, and yet they're still good friends of yours. The two of you can go for a long time without talking, but once you start talking again, it's like no time has passed. The relationship just feels secure.

Then there is the social media definition of a friend, in which the two of you have your accounts linked together on social media, but maybe you don't actually talk at all. You should not confuse social media 'friends' with real-life friends.