Understand administrative privileges
Así como os ficheiros que vostede crea, o seu computador tamén ten un número de ficheiros necesarios para que o sistema funcione correctamente. Se ditos ficheiros do sistema cambian de forma non axeitada pode facer que algo se estrague, polo que están protexidos dos cambios por omisión. Certos aplicativos tamén modifican partes importantes do sistema polo que tamén están protexidos.
The way that they are protected is by only allowing users with administrative privileges to change the files or use the applications. In day-to-day use, you won't need to change any system files or use these applications, so by default you do not have administrative privileges.
Sometimes you need to use these applications, so you may be able to temporarily get administrative privileges to allow you to make the changes. If an application needs administrative privileges, it will ask for your password.
Administrative privileges are associated with your user account. Administrator users are allowed to have these privileges while Standard users are not. Without administrative privileges you will not be able to install software. Some user accounts (for example, the "root" account) have permanent administrative privileges. You should not use administrative privileges all of the time, because you might accidentally change something you did not intend to (like delete a needed system file, for example).
In summary, administrative privileges allow you to change important parts of your system when needed, but prevent you from doing it accidentally.
Que significa «super usuario»?
A user with administrative privileges is sometimes called a super user. This is simply because that user has more privileges than normal users. You might see people discussing things like su and sudo; these are programs for temporarily giving you "super user" (administrative) privileges.
Why are administrative privileges useful?
Requiring users to have administrative privileges before important system changes are made is useful because it helps to prevent your system from being broken, intentionally or unintentionally.
If you had administrative privileges all of the time, you might accidentally change an important file, or run an application which changes something important by mistake. Only getting administrative privileges temporarily, when you need them, reduces the risk of these mistakes happening.
Only certain trusted users should be allowed to have administrative privileges. This prevents other users from messing with the computer and doing things like changing important files. This is useful from a security standpoint.