Do you use software design tools, if so, which ones?

Question

Software design

I have never used or seen that they used any design tools. I heard only out of the corner of my ear about all sorts of UML and so on, but usually all the designing takes place on paper / on the board with a marker and "in words". I would like to put this process in order, but how and with what is unknown. Only articles of the year 2008 and older are googled.
Preferably free and/or open source

Answer 1

I would like to put this process in order, but how and with what is unknown.

And why - also unknown?

Answer 2

I don't use specialized ones. For setting tasks, programmers regularly use Visio and Word.