Sealing tile.
 

We are planning on putting ceramic or porcelain tiles in our kitchen. Do you have to seal those types of tiles?

You can seal the grout if you like because you are in a wet area and have high traffic (dirt gets in the grout). The tile itself requires no sealant. However, if you use natural stone (travertine, granite, marble) then you MUST seal the stone and the grout -- on a regular basis because they are porous and absorb stains.

No sealer only works on porus surface, which ceramic is not!

Not sure what you mean, Tilemandan. There are specific sealers for porous stone . . . marble, travertine, . . . You knw hat of course, so what did you actually mean?

Recommended resealing is up to 6 months for countertops and more frequently for floors. This is a downside to porous stone not found in procelain.

The original question was if ceramic or porcelain needed to be sealed; which I answered no.

The answer is no because the op mentioned porcelain or ceramic tile.