A website contain header, footer which is common in all pages of the website. So, instead of creating header and footer in all pages, create header, footer in a separate file and include that file in all pages where it is required. In Django, include statement is used to include a file.

Step 1: Create a html file in template folder and name it as header.html, put all contents of header in this file.
Step 2: To call header use the following code:

{% include 'header.html' %}

same way you can use this for footer.

Step 1: Create a html file in template folder and name it as base.html, put header and footer contents in it.

base.html
{% include 'header.html' %}
{% block content %}
{% endblock %}
{% include 'footer.html' %}

index.html
{% extends 'base.html' %}
{% block content %}
	html file tags, contents goes here.
{% endblock %}

urls.py
    path('', views.home, name='home'),
    path('', views.about, name='about')

index.html
    <a href="/home">Home</a>
    <a href="/about">About</a>
or
    <a href="{% url 'home' %}">Home</a>
    <a href="{% url 'about' %}">About</a>