Instances of `numpy.dtype`

class are called **Data Type Objects**. Each element of a NumPy array has the same data type. The data type object can tell you the size of the data in bytes which is given by the `itemsize`

property of the `dtype`

class.

```
import numpy as np
a = np.arange(5, dtype='f')
a.dtype.itemsize
#out
4
```