If you choose to work in oils (or acrylics) you can use a wide range of supports (surfaces) upon which to paint.
Canvas (cotton or linen) is a surface with which most people are familiar – but wood panels have been used for centuries; mdf and hardboard are popular today. Watercolour paper can also be used, as can off-cuts of mountboard. Canvas (or other materials like muslin) can be glued to board or wood panels. The self-portrait above was painted on canvas glued to a board.
Whatever surface is used it must be adequately prepared. Acrylic gesso is used by most artists and is suitable for both oils and acrylics.
I would suggest three coats of gesso is sensible whatever the surface. Paint each coat in the opposite direction to the last and allow each to dry before applying the next.
Ready prepared shop bought canvases and boards have gesso sprayed on, so is usually very thin. I always apply extra coats.
An alternative to the ‘art gesso’ bought in an art store is the ‘primer/undercoat’ for oil paint that you can buy from your local DIY merchant – if the tin tells you that your brush can be cleaned in water it is acrylic based – just as effective, but much cheaper than ‘art gesso’