This is my latest game from the archive. Here is the game position.
In this position as black, I played Rd8 which give 0.50 advantage to white but the best move was a4 which give 0.80 advantage to black. I know it is pawn pushing but what we actually gain by it? Maybe space, my guess.
I have difficulty understanding the eternal motive of pawn pushing towards the enemy king on the event of opposite side castling. It is certainly not running, it must be something else. I just can't get it. So, on that part, I am making a lot of moves I don't understand or am confused and computer evaluation after the game agrees with me. It is getting such a headache on me. Please, help!
Moreover, since this is a positional or strategical concept, I can't even understand "must be played" pawn move according to computer evaluation, since the end result is not a material gain.