The word post has several meanings:

1. A strong piece of wood, metal, or concrete set upright in the ground. A fence post holds up the fence wire. A signpost displays directions or information. Goal posts mark the ends of a football field. These posts are sturdy because they need to stay firmly in place, often supporting weight or marking important boundaries.
2. To put up a notice or message publicly. You might post a flyer about your lost dog on community bulletin boards, or post a photo on social media. When teachers post grades, they make them available for students to see. Before the internet, people posted paper notices on walls and boards. Now posting often means sharing something online, but the core idea remains: making information available for others to see.
3. The mail system, especially in British English. “Sending a letter by post” means mailing it. A post office handles mail delivery.
4. A job or position, particularly in military or formal contexts. A soldier might be assigned to a post overseas. A diplomat receives a posting to a foreign country. The word suggests a specific place or role where someone has responsibility.