Ribosomes are found in two main locations within the cell: freely floating in the cytoplasm and attached to the endoplasmic reticulum (ER).
When ribosomes are attached to the ER, they are involved in synthesizing proteins that are either secreted from the cell or inserted into the cell membrane. These ribosomes are known as bound ribosomes.
On the other hand, ribosomes that float freely in the cytoplasm are involved in synthesizing proteins that will be used within the cell itself. These are known as free ribosomes.
In summary, ribosomes are essential cellular structures that play a crucial role in protein synthesis, and their location within the cell determines the type of proteins they produce.