In baseball, when a batter hits a ball and it isn't caught, he runs for first base. If he gets there before someone grabs the ball and throws it to the first baseman, he is safe—he can stay on base and try to continue around the bases when another batter hits a ball.
But if the first baseman gets the ball and touches the base before the batter gets there, the batter is out.
As you can see in the picture above, the batter reaches first base before the first baseman gets the ball, and so the batter is safe. He can continue.
From this part of baseball we get the idiom get to first base. See the definition and examples below.
get to first base, v. phr. To succeed in the beginning. Also: reach first base. This common sports idiom comes from baseball. To score, players must hit a ball and run around three bases to a fourth, called home plate. With a small hit, players can run to first base. With a bad hit, they can’t get even that far. This idiom is used figuratively, outside the sport. It is also often used in the negative: not get to first base.
• Kim hopes to get hired as a teacher at the school, and she’s made it to first base: She has a job interview there tomorrow.
• Our company tried to open a second office, but we didn’t even get to first base. We couldn’t find a good building.
