There are two main injections that GScripts uses: Menu Manipulation & No Click Walk. You can enable these by clicking on the DreamBot Settings button (bottom right-hand corner of the client, the two wrenches icon), going to the Injections Tab and checking the box next to both options.
Menu Manipulation
Menu Manipulation is used to interact with the game's menus in a controlled and efficient way. Specifically, it involves modifying or prioritising the menu entries (for example, the actions that appear when you right-click something in-game) so the bot can reliably choose the correct action.
This also applies to the game tabs like inventory, prayer, combat style, spell book etc. There are some features on scripts like One Tick Flick that require Menu Manipulation to be enabled to use. If the setting is enabled, but Menu Manipulation isn't enabled, the script will treat it as it's disabled.
GScripts recommend using Menu Manipulation with all scripts, and it is a requirement for certain scripts/features. An example is GFightCaves which requires Menu Manipulation if your account is a 1 defence pure.
No Click Walk
No Click Walk is pretty much exactly the same as Menu Manipulation, however instead of the mouse needing to move to a location to click to walk/run. The bot sends the packet to Jagex with information of where you "clicked" without needing to move the mouse. While not required to be enabled for any script, we recommend also having this turned on.