Ethernet port to Wireless LAN?

I have a laptop with in-built wireless LAN adapter. I also have an ethernet port of LAN through ADSL modem. Presently I connect my laptop to LAN through ethernet port using RJ45 cable. This restricts my movement as I have to keep my laptop near the LAN port. I am searching for a device which can convert ethernet port of physical LAN to wireless LAN so that I need not connect my laptop to ethernet port instead I should be able to use LAN on my laptop anywhere in my house without any physical connection. Is there any device? Please let me know. Thanks in anticipation.