optimal capital structure means using the resources of capital optimally, at is where they can utilised properly.

target capital structure means investment made in the certain project so that they can utilise the resource of capital properly.

optimal capital stucture is that where the firm value is high and the wacc of the firm is low and that capital structure a firm can follow constantly and that capital stucture not become a burdon on firm.

very carefully

capital structure is the structure/form/shape/component of total amount of capital owned by a company .... means the total issued or subscribed capital whether its in the form of ordinary shares, PTCs ,TFCs, etc

optimal capital structure is the such amount of capital which a company maintains while seeings its cost.

best universal capital structure for all companies?