Attachment Options:

A reliable pin. Effecient, light, cheap and secure when attached, although its sharpness may be an issue in some scenarios.
Can be clipped or pinned onto clothes. Avoids creating pin holes in your garments, although it does come with a backup pin. However, it can only be attached at the top of a piece of clothing such as a pocket.
Rotating Clip
A clip that can be rotated to fix to the side or bottom of a piece of clothing, or attached with the included pin.
A strong magnet is placed behind your clothing, holding the badge in place. This reduces damage to the garment while allowing you to freely position the badge. Not recommended for use by individuals with pacemakers.
For ID cards and conference badges, lanyards are a popular option. These are highly visible and easy to use.
Retractable Cord Primarily to suit ID cards and leather ID wallets, these retractable cords allow the card to be carried on the belt then drawn out, up to 70cm, easily and quickly for display or use.