Step 1. Add referer middleware (in settings.py file)

MIDDLEWARE = [
    'referer.middleware.referer.RefererMiddleware',  # here
    'django.middleware.security.SecurityMiddleware',
    '...'
]

Step 2. Add referer context processors (in settings.py file)

TEMPLATES = [
    {
        'OPTIONS': {
            'context_processors': [
                '...',
                'django.contrib.messages.context_processors.messages',
                'referer.context_processors.referer',  # here
            ],
        },
    },
]

Step 3. Customize referer settings (in settings.py file) (optional)

The defaults are:

REFERER_LINK_PARAMETER = 'referer'
REFERER_DEFAULT_ID = 1
# ?referer=1

REFERER_MODEL_FROM = 'django.contrib.auth.models'
REFERER_MODEL_IMPORT = 'User'
# from REFERER_MODEL_FROM import REFERER_MODEL_IMPORT

REFERER_IGNORED_LINKS = []

Step 4. Display referer information (in .html file)

<a href="mailto:{{ referer.email }}">Email</a>
<p>{{ referer.first_name }} {{ referer.last_name }}</p>