Handing in your notice
What it really means
Formally telling your employer you are resigning, usually in a short written letter or email. Also said as giving notice or handing in your resignation. The clock on your notice period starts from this point.
Context, tips & common mistakes
Keep the letter to a few lines: that you are resigning, your notice period, and your proposed last day — reasons are optional and grievances belong in a different process, because this letter may be seen again when references are written. Tell your manager face-to-face or by call before the email lands if you can; managers remember how they found out. Do not resign until your new offer is unconditional (references and checks cleared), and be wary of resigning on the strength of a verbal offer alone.
Before your last day, confirm in writing how untaken holiday will be handled — paid out, or taken during notice — and where your final payslip, P45 and any bonus due will be sent. If a counteroffer arrives, take a day before answering. And if the resignation is heat-of-the-moment, act fast: a same-day retraction is sometimes accepted, but nothing obliges the employer to agree.