The untangling is done by grabbing the end points of the lines, represented by the dots on the screen. A minimum of two lines will be connected to each dot, although many times there will be far more. You can then slide the dot to anywhere on the screen, and the lines will shrink and expand as you move the dot.
Early levels, with just a few lines and dots, will not present a huge challenge, but the techniques and tricks learned here are important, with 50 levels available you're going to have a very busy and tangled screen the longer you play - and if you go for the premium version of the game you'll have a total of 75 Gordian knots to work through.
Developed by The Elysian Fields, you can pick up Untangled in free or paid-for variants through the AAWP App Directory.