Use the Format > Hyperlinks command to set the hyperlink style for a given field. Clicking such a field or pressing Space will open that link. Hyperlinks can be links to another record/table, web addresses, e-mail addresses, or regular files/folders on your local disk, etc.
You can explicitly specify the link type/protocol by adding one of the following prefixes:

• table://
• http://
• https://
• file://
• mailto:
• ftp://
• gopher://
• nntp://
• news://
• wais://
• telnet://
• prospero://
• res://

Links between individual records can be easily created with the Edit > Copy As Hyperlink command. After it's copied, you can paste it in any other text field in any record/table. After the first use of that copy command variant, you can use the Ctrl+C shortcut to repeat it.
Links between records can also be entered manually as text. The format is:

some-table-name, record-number

where the record-number is the physical record number in a given table.
For example:

table://orders, 4555 (a link to the 4555th record in the "orders" table)

table://folder1\receipts, 2227 (a link to the 2227th record in the "receipts" table in the folder1 subfolder)

table://11455 (a link to the 11455th record in the same table)