You can think of shares in PredIQt markets the same way you think of any other stock/cryptocurrency. The only real difference is that, with PredIQt, the price of the shares is bounded from 0 to 1 (the currency is dependent on the market's asset type, as specified by the market's creator).
All shares which are the same as the market's resolution are redeemable for 1 unit/each of the market's base currency, minus any applicable fees.
Market Order: This is the most basic (and default) order type. A market order is processed immediately at the best available, current market price.
Limit Order: Designed to give investors more control over the buying and selling prices of their trades. Prior to placing a purchase order, a maximum acceptable purchase price amount must be selected, and minimum acceptable sales prices are indicated on sales orders.