Does anyone have a good clear explanation of how this rule works and how, as a DM, it gets used? I've seen it mentioned a few times and read several explanations, but none of them seemed to do a really good job of clearly laying out how it would work. From what i've gathered, basically in a given situation a party member can say "I know a guy" that would help or be relevant to the situation at hand, then describes how they know the guy and why they could help. Then this is the part where I get confused, does the DM let the player come up with the entire back story and explanation for the NPC, or do they just take the general suggestion of the NPC and create them as they see fit? It seems like a cool mechanic, if I can figure out exactly how it works I might try it in my game, so anyone that uses it or has a good explanation would be much appreciated.

That’s not an actual rule in the game, it’s just something people do. You can run it however you see fit.

Quote from IamSposta >>

That’s not an actual rule in the game, it’s just something people do. You can run it however you see fit.

 No, I know it’s not RAW, but I know it’s a popular home rule a lot of people use,  I’m curious how other people use and run it. It’s a cool idea, but I can also see several ways it could be an issue, so before I bother going down the rabbit hole of trying it, I wanted to get some thoughts from those that have. 

In games I’ve played in the player gets to run with it as far as they run, and the DM picks up the remainder if it’s necessary. However there’s usually no mechanical benefit from whomever one knows, it’s mostly just RP stuff like “I used to know someone,” or “I heard of someone,” or “I know someone who lives way far away,” so that way the person can’t just solve whatever challenge is in front of the party for them. If there ever is to be any mechanical benefit from knowing that person, the party would have to stop and go find that person first as a sort of mini quest to “earn” their aid, and there’s no guarantee that person will actually help, at least not for free.

It allows the players to participate in the world building by adding NPCs to the population without mucking anything up for the DM.

Quote from IamSposta >>

In games I’ve played in the player gets to run with it as far as they run, and the DM picks up the remainder if it’s necessary. However there’s usually no mechanical benefit from whomever one knows, it’s mostly just RP stuff like “I used to know someone,” or “I heard of someone,” or “I know someone who lives way far away,” so that way the person can’t just solve whatever challenge is in front of the party for them. If there ever is to be any mechanical benefit from knowing that person, the party would have to stop and go find that person first as a sort of mini quest to “earn” their aid, and there’s no guarantee that person will actually help, at least not for free.

It allows the players to participate in the world building by adding NPCs to the population without mucking anything up for the DM.

 Thats helpful, thanks!

It's a little weird to me that there is no official version of this, since it exists in so many other games. 'Contacts' in Exalted and the CoD games for example.  

Quote from BunniRabbi >>

It's a little weird to me that there is no official version of this, since it exists in so many other games. 'Contacts' in Exalted and the CoD games for example.  

It kind of is in some of the Background features. Criminal, for instance, has:

You have a reliable and trustworthy contact who acts as your liaison to a network of other criminals. You know how to get messages to and from your contact, even over great distances; specifically, you know the local messengers, corrupt caravan masters, and seedy sailors who can deliver messages for you.

while Sage has:

When you attempt to learn or recall a piece of lore, if you do not know that information, you often know where and from whom you can obtain it. Usually, this information comes from a library, scriptorium, university, or a sage or other learned person or creature. Your DM might rule that the knowledge you seek is secreted away in an almost inaccessible place, or that it simply cannot be found. Unearthing the deepest secrets of the multiverse can require an adventure or even a whole campaign.

Ultimately, as a DM you have units of information that the party needs and there are various things the party can do to get those units. Information gained via a contact only differs in presentation from info gained via interrogation, or research in a library, or brushing the cobwebs off a dusty mural in a dungeon, or communion with divine spirits.

I will generally require a decent reason for the contact to exist - the backgrounds above, previous downtime in the area, relevant backstory ties, etc - and if its there I'll give some baseline info and maybe some optional stuff based on a roll.

But if a character just claims they have a contact everywhere they go whenever they want info and don't really roleplay it any other time or have any actual resources invested in obtaining those contacts, I might start charging them or flat out saying they don't dig up any new info that way.