A straight reciprocating jigsaw is what the majority of people would consider as the "basic" or "standard" jigsaw. The name of this saw just means that the blade goes back and forth as you use it. This gives a distinct advantage to the saw through hard material before the saw even entirely gets there.
More than just with how easy it is to complete your projects helping, it is also very precise, allowing for detail work. These versions are usually a bit less expensive than orbital jigsaws.