Firms do not internationalise for one reason — they weigh several. The common motives group into markets, costs, barriers and risk:
Access to new and larger markets — saturated or slow-growing home markets push firms to sell where demand and populations are rising (e.g. an MNC entering India or Nigeria for their large, growing consumer bases). More customers means more sales revenue and growth.
Lower costs of production — locating in a host country can cut costs through cheaper labour, cheaper land, or cheaper raw materials, and by producing closer to inputs. This is a major reason manufacturing MNCs move assembly to lower-wage economies.
Avoiding or reducing trade barriers — by producing inside the market (a "tariff jump"), an MNC avoids the import tariffs and quotas that would apply if it exported the finished good. Building a plant inside a trade bloc lets it sell across that bloc tariff-free.
Economies of scale — operating globally spreads fixed costs (R&D, branding, machinery) over far larger output, lowering average cost per unit and raising competitiveness.
Tax advantages — some host countries offer low corporate tax rates, tax holidays or subsidies to attract FDI; MNCs also locate to reduce their overall tax bill.
Spreading / reducing risk — operating in many countries means a recession, disaster or regulation change in one market is cushioned by others; sales and supply are diversified.
Access to resources and skills — proximity to raw materials, natural resources, or a specialised/skilled labour force can be decisive (e.g. tech firms locating R&D near skilled talent clusters).