Here reactions involving additions of H- or C- reagents are mostly represented without cations. Throughout, just two arrows are involved to reduce aldehydes or ketones to alcohols via hydride to carbonyl and carbanion to carbonyl, followed by protonation. These types of reactions are powerful in synthesis. Retrosynthetic analyses via disconnection approaches often involve steps of this kind; they are introduced. Those analyses are ways of devising syntheses by mentally breaking molecules down, then reconstructing it from accessible fragments which combine well together. Minimalist approaches to organic chemistry are valuable. Strip away the peripheral aspects and focus on the main theme.
