What version of Ubuntu do I have?

Ubuntu Linux comes in two flavors, one comes with Long Term Support (LTS for short), and it is most appropiate for servers, as you will get support for many years, according with Ubuntu:

A new LTS version is released every two years. In previous releases, a Long Term Support (LTS) version had three years support on Ubuntu (Desktop) and five years on Ubuntu Server. Starting with Ubuntu 12.04 LTS, both versions received five years support. There is no extra fee for the LTS version; we make our very best work available to everyone on the same free terms. Upgrades to new versions of Ubuntu are and always will be free of charge.

But if you want to use it as your Desktop I think it is a better option to run the latest version available, with that in mind, you need to know which version of Ubuntu you are running right now.

One of the easiest wat is to open the terminal and and then, you have a lot of options some of them are:

1

lsb_release -a

That will output something like this:

No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.4 LTS
Release:	18.04
Codename:	bionic

2

cat /etc/os-release

The output in my case is:

NAME="Ubuntu"
VERSION="18.04.4 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 18.04.4 LTS"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic

3

hostnamectl

The output should be something like this:

   Static hostname: ggarron-Latitude-3450
         Icon name: computer-laptop
           Chassis: laptop
        Machine ID: f651e642466444a7aedd9727b149d741
           Boot ID: 82a16a0f319a4983881c68144429e326
  Operating System: Ubuntu 18.04.4 LTS
            Kernel: Linux 5.3.0-42-generic
      Architecture: x86-64

4

cat /etc/issue

The output will be:

Ubuntu 18.04.4 LTS \n \l

5

cat /etc/os-release

The output will be:

NAME="Ubuntu"
VERSION="18.04.4 LTS (Bionic Beaver)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 18.04.4 LTS"
VERSION_ID="18.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=bionic
UBUNTU_CODENAME=bionic

As you can see, there are a lot of options, always check the version you are running, specially if you are thinking about start developing. I said before that for your Desktop is better to use the latest version, this is not always the true, as if you are developing it is better to run the same version of the server you are going to deploy, so always check before.