.container and .column

Question

I came across the .column and .container classes used to create columns in a CSS,HTML template.

but the main HTML code had no classes named as columns ,
how are the columns created?

is it predefined or .columns matches any class having columns as a part of the class name?

Answer 1

any class starting with . have to be called
any class starting with # called to a id auto
any class name matches HTML tag is added to that tag

Answer 2

An example of a 3 column class css definition: https://code.sololearn.com/WbCU8pf68o08/#css

Answer 3

.column and .container classes in the template must belongs to a framework like bootstrap and materialize etc.