Keep in mind that Dedekind cuts are defined _after_
defining the complete ordered field, not just rationals.
Other notions of cuts include Veronese and Peano.
The usual notion of infinitesimals as "bullets"
(iota-values) are in a sense also cuts.
(And look like line reals that a modern definition of
line continuity besides (Dedekind's) field continuity.)
They're topology's, and it's not so much however
many of them are as that they are there.
Dedekind cuts are a model of rational bounds of reals
by their usual order of the rationals, laws of arithmetic.
But, they're not "the equivalence classes of
sequences that are Cauchy", in the development:
the required sense. I.e., _after_ defining the
complete order field and Least Upper Bound axiom,
_then_ Dedekind cuts are about rational bounds,
but, they get gaplessness, which the rationals don't,
from Least Upper Bound and the development.
I.e. proofs of Dedekind's cuts being uncountable and
of the cardinality of the continuum and though only
defined by rationals that the open and closed about
them sew up, are of course only after Cauchy/Weierstrass
and Least Upper Bound.
Of course, various definitions of "continuous" in function
make the rationals or a function defined on them look
"continuous" (or meeting the definition, that arbitrarily
small differences in domain have arbitrarily small differences
in range), but conscientiously 24/7, the rationals
are countable or continuous, not both.
The line reals are countable and continuous - only one function.
The signal reals or after the rationals that simply enough
"doubling the density" of the rationals arrives at covers
for all points, besides neighborhoods, again one wouldn't
conscientiously let stray the required formal surrounds
for soundness and constancy in definition.
(This is where uncountable is after limit ordinals anyways,
that basically between the discrete so well-defined by all
the rationals and the continuous thus well-defined by
completing the signal, is limit over that, too,
that it's a special case according to the definition
of "function" of the "numbers" in the "set theory".)
The field reals are quite usual about the modular and algebra.
Most continously-variable processes are parameterized by time,
which according to a clock-principle is uniform and constant,
and thus that "geometry is motion".
One wonders such notions might be lost on the retro-finitist,
but, the conscientious formalist keeps them.
I.e. that mathematics is a truth not a game,
though that of course it's sublime.
I have here three definitions of "continuous" after various
corresponding notions of "discrete", line, signal, and field
continuity and for models of real numbers in set theory
(the model theory the function theory the number theory,
the descriptive set theory). This is called "repleteness".