DNA
DNA contains the vast majority of genetic information that is transmitted between generations in the form of a base pair sequence.
RNA and proteins in the cellular environment are also passed on in the cell. Furthermore, cultural traditions (e.g., adult milk consumption) that may or may not be related to genetic variation (e.g., lactose tolerance) are also passed on within families. (Humans are also not the only extant species with cultural inheritance.) Both of these examples can be argued to also represent transmission of genetic information.
Viruses with an RNA genome are another exception to the rule above.
Prions (infectious protein conformations) are also an exception to the rule above.
DNA is made up of a sequence (polymer) of four major base pairs (A, C, G, and T). (C can be methylated, changing its function.) (Synthetic base pairs have been created that also function as a part of a DNA sequence.)
DAPI is a commonly used stain of DNA that fluoresces in the blue spectrum under UV light.