In English civil litigation, costs are the lawyers' fees and disbursements of the parties.
In the absence of any order or directive regarding costs, each party is liable to pay their own solicitors' costs and disbursements such as a barrister's fees; in case of dispute, the court has jurisdiction to assess and determine the proper amount. In legal aid cases, a similar assessment will determine the costs which the solicitors will be paid from the Legal Aid Fund.
In most courts and tribunals, generally after a final judgment has been given, and possibly after any interim application, the judge has the power to order any party (and in exceptional cases even a third party, or any of the lawyers personally) to pay some or all of other parties' costs. The law of costs defines how such allocation is to take place. Even when a successful party obtains an order for costs against an opponent, it is usual that he may nevertheless still have to pay his solicitors a balance between the costs recoverable from the opponent and the total chargeable by his solicitor; and if the loser is unable to pay, then the order for costs may be worthless, and the successful party will remain fully liable to their own solicitors.