This is a short segment of B-form DNA
This is a spacefilling model, colored CPK, viewed from the side.
Note the 2 grooves. The major groove is the one in which the phosphates are farther apart.
This shows the 2 strands colored violet and cyan. The right-handed twist can be seen.
An endview shows that the double helix is perfectly circular, and that base-pairing occurs across the center of the helix.
An isolated view of several base pairs.