There are essentially two types of syndication: First-Run and Off-Network.

Off-Network

Off-Network is the type we saw most commonly through the late 90's and early 00's. This is where a series reaches an episode threshold (usually 100), and the rights to show re-runs are sold to any channel that wants to air them. Depending on your market, you could find the same show on Fox, CBS, NBC, The CW, etc. The Simpsons is a great example of this — it airs old seasons on multiple channels (or did, until Disney+). 

Series that fall into this bucket should continue to be tagged with their original network, as that is where the episodes first aired.

First-Run

First-Run syndicated series are shows that are not produced with any particular channel in mind by the producers. They then sell airing rights to different channels in different markets.

Lots of daytime game shows follow this pattern, including The Newlywed Game, The Dating Game, Jeopardy! and Wheel of Fortune.

Daytime talk like Donahue & Dr. Phil were first-run syndicated. Currently, Drew Barrymore, Ellen DeGeneres & The Kelly Clarkson Show are all first-run syndicated.

These types of series can be tagged with Syndicated as their original network.

Scripted shows don't have a huge presence in first-run.

As a note, these rules are not retroactive to older series, and we will not apply them as such.