An overview is given on the state-of-the-art in synthesis of sequence-controlled and sequence-defined oligomers and polymers. These materials constitute chains in which chemical information is encoded along the backbone either as multiblock copolymers (controlled) or as monodisperse sequences of single monomers (defined). Focus is placed on reversible-deactivation radical polymerization techniques as these give access to a broad variety of chemical functionalities and allow for simple and fast synthesis procedures. Sequence-controlled and -defined materials have the ability to re-shape materials chemistry due to their close resemblance to biopolymers regarding structural uniformity. The field is at the edge of being able to start exploring the distinct properties that such synthetic macromolecules may have.