What’s the meaning of short and long in investment terms?

Short - Bearish on price, sell high now to buy low later to realise a profit.

Long - Bullish on price, buy low now to sell high later to realise a profit.​​​

Assuming these are logical people... A few things to note:

(1) the aim is to buy low, sell high (in order to make $ - although from many people's behaviour, it seems as though they are doing the opposite).

(2) on most platforms, you dont have to do it in that sequence. You can buy low, and then sell high. OR you can sell high and then buy low.

When people say they are long a particular stock, for example "I'm long apple", it means that they expect Apple's stock price to go up in the future. That means they are going to buy the apple stock TODAY (when it's lower), and sell it in the future (when it's higher). So LONG = BUY

When people say they are short a particular stock, for example "I'm short apple", it means that they expect Apple's stock price to go down in the future. That means they will sell the apple stock TODAY (when it's higher), and buy it back in the future (when it's lower). So SHORT = SELL