Bodysuit with lapped shoulders or shoulder placket opening.
Long or short sleeves.
Several types of collar: crew neck, turtleneck, ruffle collar or stand-up ruffle.
Two possible finishes: elastic bias binding or ribbing.
The basic bodysuit to decline with the seasons
The bodysuit could also be used as a swimsuit (in particular the long-sleeved, turtleneck version as a sun protective swimsuit). In this case use a specific swimsuit fabric for all parts and keep the crotch opening with the snaps or close this opening by sewing the front and back to the crotch together.
What you will practice with this sewing pattern: how to finish with ribbing or with an elastic bias binding, how to sew lapped shoulders or a shoulder placket.