Granting landed titles to vassals

[Neon Lotus]

So I just granted a landed title to a vassal, hoping it would improve his relations with me so he would pay his taxes to me instead of the pope.

Thing is, it removed him from my vassals, so I now realize I don't understand this part of the game :(

What is granting landed titles all about? Why would/wouldn't you do it?

[that guy]

Granting landed titles means you're giving your land to your vassal. Are you sure that it's worth losing that land and its income to potentially get more income from your vassal?

Also, I'm going to guess that you're playing an Irish tribal chief and you granted a province to one of your bishops. That makes the bishop the same tier as you, a count. Since he is now the same tier, he will not be your vassal. You cannot vassalize anyone of the same tier.

If you are a duke (or high chief in your case), you can grant provinces and whoever you grant them to will remain your vassal. However, it's not a good idea to grant them to a bishop because they're a different government type and you would only do so if you wanted to help the bishop become the pope (in which case he would also no longer be your vassal).

[Ea0]

There are different tiers/ranks of titles.
If you grant someone a title of your own tier, they will become independent.
If you give out titles lower than yours, they will stay your vassal.

http://www.ckiiwiki.com/Vassals#Landed_titles

[Manthexxx]

The reason you would do it (give lower tier title to vassal) is because if they are strong enough they might go expand on their own for you, especially later in the game when you are the emperor and have king vassals, they might press de jure claims in their kingdom and they gain that land, which means *you* gain the land because they are yours.

The reason you wouldn't want to give your vassals landed titles is they might rebel against you if they dislike you and are strong enough.

If you wanna ensure you don't get a rogue dynasty in your empire, grant people viceroy kingdoms (requires a law change as an empire, invest in legalism) that means the kingdom will revert back to you upon their death.