What can you tell me about ceramic tile cracks over concrete slab foundation?

[QIS]

Concrete moves whenever it expands or contracts, that does not means its going anywhere at a "rate". Floating a membrane or the tile material itself over a cracked area as I described above is one technique. It does not matter what the membrane is; it has to be installed with avoiding crack transference in mind; otherwise it will not hold.

[Pitt Chick]

Curious.

We have had the same sort of cracking, but our slab was laid in 1966.
I doubt IT is still moving... so what else can it be?

[QIS]

Expansion and contraction! Like I wrote above, concrete moves; that does not mean its going anywhere!