I have craft books from various different countries, and the names for these sewing items seems to vary even among English-speaking countries. What are these things called to you? (I'm mainly interested in English, but other languages are cool too)
It's the machine you use to neaten raw edges of seams. It trims the edge of the fabric, and the home versions use four threads to seal it. To me this is an overlocker. The verb is to overlock (not to hemlock as one girl in my school sewing class kept finding herself saying!)
You use this tool to remove unwanted stitches and cut buttonholes. To me it's an unpick.
This is the seam you use on the inside leg of jeans. You sew the fabric wrong side together (ie the opposite way you normally do) with an extra-large seam allowance. You trim one half of the seam allowance back to a few mm away from the stitching. You then fold the other part of the seam allowance in half, press it, and then sew it down with top-stitching to give an extra-strong seam. To me it's a run and fell seam. (A french seam is similar, but you trim both sides, and fold the reinforced bit inside rather than fold it over on top).
You use this stuff to neaten raw edges and as decoration. You make it by cutting strips on the cross/bias of the fabric, or you can buy it ready-made in a roll. To me it's bias binding (which is also a fun word to say)