How many gates do we need in a transistor?

The migration from single-gate to multiple-gate SOI transistors is inexorable but still includes a number of hesitations and dilemmas. In this context, we review the main motivations, technological achievements, physics-related implications and future challenges. Specific aspects governing the operation of multiple-gate transistors are discussed with the aim of clarifying the strategic trends. The physics mechanisms are briefly evoked. The road is difficult with many turns; hopefully, it looks long enough. Generic milestones are: nano-size, multiple-gates, innovative ideas and multi-facet SOI technology.