In general, babies don't really need to get toys, but it is always fun to watch baby explore the world and learn from the right toys. Some toys are just for fun, but these are generally not useful until baby is about a year and a half or two years old. Baby developmental toys, on the other hand, can be played with by babies as young as three to six months old. These toys are designed to help them learn many of the gross and find motor skills that they are going to learn anyway. They are just a more fun way for mom and dad to be involved with it all.
Some of the first things that can be learned from baby developmental toys is how the hands and feet work. These are gross motor skills at first. You may want to get something that baby can kick. This will be one of the first things they will do. Some bouncy or vibrating chairs have hanging toys near the feet that baby will kick. They learn cause and effect as well as that those feet are theirs and that they can do things with them. They may concentrate very hard on kicking once they realize they can do it and it may keep them occupied for a very long time, or at least until they feel hungry.
The next set of gross motor skills baby is going to work on in regards to baby developmental toys would be that they own those hands and that those hands can do the same things the feet can do. They will swing their arms at hanging toys too, though they will overshoot the mark quite a bit at first. They also learn, as they did with their feet, that if they hit something it will move or make a noise. This is a great discovery for baby and one you will cherish. You may soon find them staring at their hands as they learn what they are and that they have control over what they can do.
After this, you should think about play mats as baby developmental toys that can help your baby with gross motor skills. They should spend some time on their tummy each day (but never while sleeping) so that they can learn to lift both head and shoulders off of the floor. They also learn that they can roll over if they use arms and legs in certain way. These floor mats can be multi-functional baby developmental toys as they have hanging toys and even music included. Most babies love these and use them for quite some time at different levels of development.
Baby developmental toys are also useful when baby starts to develop fine motor skills. One of the first of these will be when they learn to use the pincer grasp. This is the index finger and thumb working together to pick up something rather small. Each baby will do this at their own rate, and there are toys that help with this without baby having to pick up something that they could then put into their mouth and choke on. Look for toys that allow baby to grasp and move things and you will provide hours of learning and entertainment for everyone.