There are many kinds of Fishing Lines
The newest advancement in lines is Braid.
This can be a multi strand Dyneema, usually 3 individual strands.
Each strand is coated to give it an even flexible feel.
Dyneema Braid is exceptionally strong and abrasion resistant.
Mono is probably the most popular with a lot more than 60% from the market attributed to this kind of fishing line.
Mono is affordable soft and supple , it can be used for a lot of kinds of fishing.
Probably freshwater would be the place probably to see its use.
Another type is fluro carbon.
This is excellent line but very costly.
Most fishermen apply it leaders around the end of the main lines.
Flyfishing line ,has moved a long way in the old cat gut and oiled silk.
Nowadays it's PVC of manufacture, this lines are heavy as no weights are used when fly fishing.
For sea fishing Braid has become very popular as it is incredibly strong and abrasion resistant.
It is a lot more expensive, fishermen who are not competent playing a fish would be the main users of this line.
All fishing lines need to be replaced at least once a season as salt and Ultra violet light includes a detrimental impact on the product.
There are many brands in the marketplace but of course you do get that which you pay for.