Was gonna start this as what could you not do without but decided to add the word "item" to avoid the obvious replies.
These days we have the mobile phone, computers and other high tech stuff. Yet think about it. Many of these items are recent and have killed some old pastimes and values. What would you most miss?
Me i think electricity as we would be well stumped without it.
Also do you have an item from yesteryear which you still use and swear by today?
Mine has to be my old singer hand sewing machine which comes in handy for tiny items like dolls clothes which the electric version is far too fast.