Their expanding population outgrew the productive capacity of their limited land. They had the option of conquering more land or trade. They chose the latter.
Their traders took it with them.
Traders took the alphabet with them to pass on to other people.
They expanded from trading Phoenician goods to carriage trade- that is they also shipped and traded goods from other as well as their on.
To supplement their own products with products they did not have/make. Also to on-trade them to other areas.
There are few different goods that are brought from other regions. You can buy clothes, dishes, jewelry and animals.
They initially traded their own produce of timber, gems, metals, cites and foodstuffs, then expanded into carry trade - shipping commodities between other producers and markets.
We are often told that the Phoenicians invented the alphabet. Regardless of who put pen to papyrus to create it, the Phoenician contribution was none-the-less major and critical. They were the major sea-traders of the Mediterranean, and they went everywhere. When the Phoenicians began using the alphabet as a simple and easy way to keep track of their trades, it was exposed to everyone. Also they show the other countries that ships could travel around the globe trading important commodities. Phoenician mariners sailed to Mediterranean and southwestern European ports. The Phoenicians were the great merchants of ancient times. They sold rich treasures from many lands.
To communicate over distances, and to record trade.
You learn both the the Phoenician and English alphabets and the Phoenician and English languages. Then you can move from one to the other.
they bought them from other traders
It developed from trading Phoenician goods int carriage trade - that is shipping locally-produced goods between other centres.
People around the Mediterranean Sea welcomed them as traders, as did the Mesopotamians. The Romans saw the Carthaginians (a Phoenician city) as rivals and destroyed them. The Persians took them over to use their naval and trading power. The Macedonians later did the same, and so did the Romans.