There are direct air services from London and other European cities to Inverness. The airport is at Dalcross, seven miles east of the city. Both buses and taxis are available into town. From Europe it's often cheaper to fly to London, and then catch a train or bus north. There are reasonably good train and long distance buses from major cities around Britain.
Straddling a nexus of major road and rail routes, Inverness is an inevitable port of call if you're exploring the Scottish Highlands by public transport. Buses and trains leave the city regularly for communities across the far north of Scotland. The bus station and train station both lie off Academy Street to the east of the centre.
Inverness is small enough to visit on foot. Alternatively, explore the city (in good weather!) on the open-topped double-decker bus. You can buy purchase tickets on the buses, which leave from Bridge Street near the tourist office.