Tunisian Simple Stitch (Tss)

Intermediate Tunisian

The basic Tunisian crochet stitch, worked with a long hook in two passes per row, producing a dense, woven fabric.

Using a Tunisian hook long enough to hold a full row of loops, chain the number of stitches your pattern calls for.
Forward pass: insert your hook into the second chain from the hook, yarn over, and draw up a loop, leaving it on the hook; repeat into each chain across the row, leaving every loop on the hook without working any of them off yet.
Return pass: yarn over and draw through 1 loop only, then yarn over and draw through 2 loops at a time, repeating across the row until 1 loop remains on the hook — that remaining loop is the first stitch of the next row.
For every row after the first, forward pass: insert your hook under the second vertical bar from the right edge, yarn over, and draw up a loop; repeat across, working into each vertical bar, leaving all loops on the hook.
Return pass: work off the loops exactly as before.

Tunisian crochet is never turned — both the forward pass and return pass are worked with the same side always facing you, which is what makes the fabric so dense.
Because every stitch stays live on the hook until the return pass, Tunisian crochet needs a long hook, or a cord-extended hook, rather than a standard-length one.
The vertical bars you work into on later rows are easy to spot once you know to look for them — they're the front-facing loop of each stitch from the row below.