Colloidal 2D semiconductors, so-called nanosheets and nanoplatelets, are only a few atom layers thick and exhibit promising optoelectronic properties that are chemically tunable between visible to infrared wavelengths. 2D semiconductors are strongly quantum-confined in their thickness dimension, resulting in the control, and fine-tuning of their narrow absorption and emission features. A key advantage of colloidal synthesis methods is the ability to grow not only ultrathin van der Waals structures but also intrinsically isotropic materials (e.g. cubic lead chalcogenides) into a strongly anisotropic crystal shape by the virtue of surface ligands and reaction conditions. I will touch on the synthetic tailoring of colloidal 2D semiconductors, on their integration into innovative optoelectronics (e.g. directed emission and polymer-encapsulation) and on their superior potential as single photon emitters for photonic quantum technologies.