Underscores in magento variables

magento

Solution

Underscores are used in two different ways in the Magento codebase.

In classes an underscore at the beginning of a variable or function name indicates that the variable is private or protected.

Within templates, most variables that are used locally are prefixed with an underscore. This indicates that the variable is "private" to the template.

Problem

I can't understand and find information why there are sometimes underscores in variable names, for example `$_links` instead of `$links`. What does it mean?

Original source