A home inspection is meant to detail problems with a house and if they’re serious enough to prevent a sale. The three main points of an inspection are physical condition, items in need of repair or replacement, and remaining useful life of major systems. No home is perfect, even new construction, so be prepared that there will be many little things that are found, but you are looking for major issues & safety concerns and things that may be found that you don't want to deal with to repair or replace, then the seller can be asked to repair/fix or reduce the price to compensate for you to do after the sale.
It’s a good idea to be present during the inspection: you can ask questions and the inspector can point out areas of potential trouble and offer maintenance tips. It's also easier to see and understand any concerns, issues if you can see it in person.
Expect an inspection to take 2-3 hours and to cost $300-$400, depending on size, age, location & if you are getting extra items inspected (radon, mold, sewer, etc), there will be an additional fee to have each of those inspections completed.
It's important o choose a good & qualified inspector. The best resource is to ask your Realtor or get recommendations from other people you know who have used one recently. If you look for one online, Be sure to ask about references, memberships in professional associations, training, and experience. It's best to use an online service such as HomeAdvisor, Angie's list or the Better Business Bureau.