This text contains the findings of some of the world's leading researchers on high Tc superconductivity, including considerations of the order parameter and the pairing conditions. Both theoretical and advanced experimental results are outlined. Considerations of d-, s-, or more complicated order parameter symmetry are discussed at length, serving as a benchmark for an overall view of the field as of April 1998. Many of the results presented are new and have neither appeared nor been discussed previously. Interesting experimental facts are given on junctions and fluctuations, both in the presence and absence of a magnetic field. Electronic, optical, magnetic and transport properties are discussed.