It is a good idea to periodically update your Raspberry Pi so you have the most recent version of your packages and patch security vulnerabilities. The easies way to do this is thru APT (Advanced Packaging Tool).

To get started, open up a Terminal window. We will want to make sure the APT has the most recent list of available packages. So first we will run:

sudo apt update

Next, run the following command to upgrade to the latest versions available:

sudo apt full-upgrade

We use the full-upgrade rather than just the basic upgrade so that any dependencies will also be updated.

A couple things you will want to keep in mind. First, this is only for day-to-day upgrades. It does not work on major releases.

Second is that APT will not check if you have enough disk space to run. Any previously downloaded package files will be kept in /var/cache/apt/archives. But you can easily remove them by running:

sudo apt clean

Reference: https://www.raspberrypi.org/documentation/raspbian/updating.md