The Georeferencer GDAL plugin is a core QGIS plugin, meaning it will be installed by default. It is an implementation of the GDAL_Translate command-line utility. To enable it, navigate to Plugins | Manage and Install Plugins, and then click on the Installed tab and check the box to the left of the Georeferencer GDAL plugin:
Once enabled, you can launch the plugin by clicking on Georeferencer under Raster:
The Georeferencer window has two main windows: the Image Window and the Ground Control Point (GCP) Table ...