(elaborated from Contacts at d20srd.org)
Contacts are supporting characters, whom the player characters develop relationships with over time. These NPCs are stable, ongoing friendships or business relationships who offer some utility to the adventurers.
A designated contact is story-stable, and will not be killed or taken out of the game unless the player character deliberately pushes them away. Existing minor NPCs may be selected as contacts, but major supporting characters are not appropriate as contacts.
The more important the contact (either in terms of social standing or story impact), the less available they are. It is generally more useful to choose clerks and valets instead of prominent officials and nobles.
Different character classes accrue contact points at different rates. The player may designate one contact for each full contact point accrued. There are three types of contact: Information, Influence, and Skill. Players must choose the contact type right away, but can leave the identity of that contact for a later time. At any point in the story, the player can declare the identity of a contact (with GM approval).
Everline is a bard, so she gains half a contact point every level. Upon reaching level 2, the player assigns her first contact as an Information contact. Later in the story, the player sees a need for someone with the earl’s ear, and suggests that Everline has become drinking buddies with the earl’s barber, who becomes her information contact. The barber may not have any influence with the earl, but the earl is a chatty patron, giving the barber interesting gossip about local affairs.
Once assigned, the contact remains on friendly (or at least favorable) terms with the character, and may be called upon repeatedly as needed. If extenuating story circumstances result in the contact’s demise or incapacity, the GM will generally refund the contact slot. If the contact meets a bad end due to the player character’s actions, the point may not be refunded – it is wise not to burn bridges.
Information: people who hear things – could be general town gossip, or focused information about current events (troop movements, weather, court intrigue)
An information contact is generally a commoner or an expert with one-third the class levels of his PC friend. It’s okay to give such a character a few levels in another class such as wizard, rogue, or fighter if it’s reasonable for someone in the contact’s position to have this experience. Most information contacts spend their skill points on interaction skills such as Diplomacy, Gather Information, and Sense Motive.
Influence: people who know people, and can put in a good word/ set up a meeting – or interfere on the character’s behalf
An influence contact has one-quarter the class levels of his PC friend, almost always in an NPC class (adept, aristocrat, commoner, expert, or warrior) unless the character is in an environment such as a wizard’s academy where almost everyone has specific class levels.
Skill: people who know things, particularly Profession, Craft, and Knowledge skills that are uncommon among adventurers
A skill contact is generally an expert with half as many levels as his PC friend. He has maximum ranks in the skill he is best at, and his highest ability score is in the key ability for the skill in question. A skill contact always has the Skill Focus feat related to his field of specialty.
Gaining contact points
The more sociable classes gain contact points faster. Consult the GM if your character’s classes do not appear in the list below.
Group A (bards) = .5
Group B (clerics, paladins, rogues) = .34
Group C (fighters, sorcerers, warlocks) = .25
Group D (barbarians, druids, monks, rangers, wizards) = .2
Every time the player’s character accrues a full contact point, the player chooses what the contact type. They may assign the actual identity of the contact at any point thereafter. Once assigned, the contact is set until further notice.