Sharing links to cards, boards, comments and actions
You can easily obtain and share a link to a board, card, comment or action in Trello. If you are linking to a private item then the person you are sharing the link with must be a member of that board in order to open the link. Links to team visible items can be opened by members of your team but one will still have to be a member of the board to collaborate on the linked item. A link to a public item on a public board can be opened by anyone that has been given the link.
Linking to boards
To obtain a link for your Trello board, open the board's menu, then click "More", and copy the link to your board.
Link to a board from the board's menu.
Linking to cards
To obtain a link to a card on your board, open the card, click "Share and more..." from the lower right-hand corner of the card back and copy the link to your card.
Linking to card comments
To get a link to a specific comment, right-click the timestamp link under the comment on the card back and select your browsers "Copy Link" option.
Linking to card actions
You can also get a link to other actions on a card, like for example a card attachment. To obtain a link to a specific action, right-click the timestamp link under the action on the card back and select your browsers "Copy Link" option.