Portfolio
Your portfolio is a list of all the shares you currently own or have previously bought.
Portfolios vary slightly on different websites and in different software, however they all contain these basic aspects;
Example
(screenshot courtesy of ADVFN.com)
Portfolios can usually found online on stock market news websites. However if you purchase stock market software you will nearly always find a portfolio section in there.
It is free to sign up for an online portfolio and an excellent way of tracking what shares you have acquired and what shares you have made profits and losses on.
Remember, you don't actually have to buy the stock for real to enter it into an online portfolio! Therefore they are a great way to practice before becoming a trader or just to play around with to get an idea of how the concept of the stock market works. For an easy to use practice portfolio that covers US stocks use Wall Street Survivor.
A portfolio will help you keep track of what stocks you currently own in a clear manageable way therefore avoiding confusion and improving your control over your money. A portfolio is also a good way of looking back over previously owned stocks and analysing your mistakes and successes, potentially helping improve decision making in the future.
Watchlist
A stock watchlist is a list of stocks that you are currently interested in. Watchlists are a good way of storing your preferred stocks (saving you time entering each stock individually over and over again) and over viewing their performance.
The idea is that when a stock in your watchlist hits your target price you would then buy it and enter it into your portfolio, consequently not mixing your wanted stocks (watchlist) with your owned stocks (portfolio).
Watchlists come hand in hand with portfolios, where you find an online portfolio, you will find a watchlist.
Like portfolios, watchlists are also free when you sign up to a website which has practice accounts.