Linux Package Managers

There are two main package managers on Linux, there is YUM and APT. Each distribution will use one or the other. They do have similarities in that they need to be run as root or with sudo, they work from repositories specific to the distribution and its release channel (stable, beta, dev), you need to run "update" and then "upgrade" and they are very reliable.

There is also DNF, which is an improved version of yum and is currently used by Fedora. Then there is zypper which was developed by the suse community.

APT

Used by: Debian, Ubuntu

I believe, in general apt has replaced apt-get and made things simpler. Some example commands:
sudo apt update
sudo apt upgrade
sudo apt search vsftpd - to find a vsftpd package
sudo apt install apt-file - this is not installed by default
apt-file search vsftp - find a file called vsftpd and report the package it is in

YUM

Used by: CentOS, RedHat

sudo yum update
sudo yum upgrade
yum search vsftpd - to find a vsftpd package
yum provides vsftp - find a file called vsftpd and report the package it is in

zypper

Used by: openSUSE
It is worth noting that openSUSE also supports apt but zypper is recommended.

sudo zypper update - this is the same as "update and upgrade"
zypper search vsftpd - to find vsftpd package
cnf ifconfig - find a file called ifconfig and report the package it is in
zypper search --provides --match-exact vsftpd - find a file called vsftpd and report the package it is in