You can mod GTA 5 in two ways: With .ASI mods and with .DLL mods. Before installing any GTA 5 mods, you'll also need to download some extra add-ons like Script Hook V ...

Script Hook V (or ScriptHookV ... as that can result in account suspensions or permanent bans. The download file will be in a compressed format, so you will need an extraction tool, such as ...