What does font weight mean exactly?

Font-weight defines the thinness or thickness of a font. The ranges are 100 to 900. Normal font is 400. 700 is bold. So 900 would be an "extra bold" and a 100 would be an "extra light". These are (to my knowledge) only used in increments of 100. Hope this helps!

So basically this just makes your font text bold increase or decrease in thickness correct? and every time I go by 100 up it still stay looking the same thickness in other words so when I changed it to 200 and did a comparison of 100 I see no difference is thickness is that suppose to happen because i'm using w3schools.com editor to understand this visually but when I go up to over a couple of 100s up which takes a couple of 100s for it to be notice in boldness in other words I notice the change of thickness of the text changes when I enter 900 not sure if that makes sense how i'm explaining it to you I just thought if I start with 100 it will be normal and go to 200 it will get bold and if I go in 300 it will get thicker width and if I go up to 400 it will get more thicker in boldness in width and if I go up to 500 it will get bigger by width So is that what the element means ?

So the higher I go by 100's example 100,200,300,400 etc.. it wont increase by boldness visually? and when you say weight I think of weight out side of coding terminology like how much something weighs heaviness like a person who weighs 185 pounds etc.. what does weight mean in coding terminology and sorry its been months since I been on here so I got the element and property mixed up. Does this property suppose to stretch a text on a web page in a bold way? I still thinking about this visually.

Ok its making more sense to me now :) so basically font weight means thickness of text correct? aka boldness of text correct ?

Thank you your the best Jennifer. :)