Repository is a place where multiple databases are provided . apt :- A Debian tool used to manage packages. When a user installs a package on a system, it also searches for and then installs or upgrades all the necessary dependent packages to make the package work. The actual command is apt-get.
Considering this, what is a repository for Linux?
RPM is the package manager tool which installs the package. YUM is a repository management tool which will fetch the appropriate package for your particular version of Linux(along with all other required packages). Repositories is an organized collection of packages that YUM uses.
What is a PPA repository?
A Personal Package Archive (PPA) is a software repository for uploading source packages to be built and published as an APT repository.
What is the package manager for Ubuntu?
Ubuntu is based on Debian and all software packages are .deb files. Moreover, dpkg command (Debian package) is the low level package manager for Debian files (.deb). It is the backend of apt (and aptitude), which in turn is the backend for GUI utilities like Synaptic Package Manager and Ubuntu Software Center.