Every player at the beginning of his chess carrier thought that the positions with opposite color bishops are draw. So avoiding such positions seemed very good strategy if one is playing for a win or if one was trying to draw that was what he was striving for.

When I was 13 years old I played against one international master ( I had 2150 rating points back then), I got worse position after the opening and during the middle game I was trying to equalize. Finally I got in an endgame with rooks and opposite color bishops. Immediately after reaching that position I offered a draw, thinking that due to presence of the bishops my opponent didn’t have chances to play for a win. He declined my draw offer and that hit me as a hammer. I was so sure that I will draw against international master, and achieve great result on the tournament. After that game I studied opposite color bishops positions very carefully.
There are 3 types of opposite color bishops’ positions: when there are only bishops on the board, when there are rooks without queens or queens without rooks, and when there are opposite color bishops with queens and rooks.
First type of positions usually ends in draw. Most of them end peacefully and none of the opponents tries to win, since there are no possibilities to play for win. Both players put their pawns on the same color as their bishop and the opponent can’t attack them. Of course there are many examples when one side wins but the majority of the games are draw.

Second type of positions usually is richer with play. There is draw tendency, but if the player who has slight advantage decides to play he has more chances to win the game. In these positions there is possibility of creating mating threats. That is why the safety of the kings is very important. Usually the advantage of one of the sides is long lasting, but not always enough for a win.

Third type of positions is very sharp. That is mainly because “second” of the bishops can’t control the squares that are under the control of the “first” bishop. This means that if one player starts attack towards opponents king then he will attack with one more piece, because the bishop one the defending side can’t control the opposite squares. There is one rule here: the side which is attacking has the advantage!