you're position at the table in a hand , the button SB BB , in the field or cutoff often determines how one should act with playable cards, a player in a later position has a advantage that he/she will have more information with which to make decisions than players in early position & a decent hand becomes stronger if more fold prior to your turn. so a player betting in early position is representing a strong hand but by just calling the BB (or a small bet) a moderate hand looking for flop help. the BB has advantage pre flop (acts last)but the button player has the advantage post flop overall.