Sterilization

Sterilizing and sanitizing solutions are used in plant tissue culture:

To sterilize working areas (for example clean boxes, laminar flow hoods, benchtops, plates), tools (for example forceps/tweezers, scalpels, knives, stirrers), and culture vessel media, closures and exteriors when about to work on them. In all these cases the aim is to achieve a 100% kill rate for bacteria, fungi, their spores, and viruses. This is true sterilization.
To eliminate all unwanted organisms (bacteria, fungi, their spores, and viruses) from the surface of explants prior to or during tissue-culturing. Desirably, the aim is still to achieve a 100% kill rate for these organisms, while simultaneously not damaging the cells of the explants. This is also called sterilization, or disinfection.
To reduce the unwanted organisms on the surface of exposed human skin (hands, fore-arms), but not to damage the underlying skin. This is a higher priority than damaging explant cells, and is called sanitization or disinfection. 100% kill is not achievable. 70% alcohol, 10% household bleach or 3% hydrogen peroxide are commonly used.

Various methods or chemicals are used for these purposes, including:

Heat (autoclaving in water or steam to 100°C and above {say in a pressure cooker} for at least 5 minutes). Kills explants, too!
Microwaves (autoclaving with heat too, but the microwaves preferentially target and heat things with water content like living things). Kills explants, and you also if you fit into a microwave oven. Approved by NASA for 100% sterilizing interplanetary vehicles.
Alcohol, specifically either 70% ethanol C2H5.OH or isopropanol C3H6.OH. Methanol CH3.OH produces many poisonous products and should not be used. Alcohol acts by denaturation (see Wikipedia) of proteins, causing cell death of bacteria and fungal cells. Spores may have sufficiently strong walls to resist denaturation, so alcohol is not as effective as other chemicals.
Hypochlorites OCl- (household bleach 10% sodium hypochlorite NaOCl, swimming pool disinfectant calcium hypochlorite Ca(OCl)2). These are common household chemicals available from supermarkets or pool stores (in granular form) respectively.
Hydrogen peroxide (3% H2O2), also a common household chemical available from pharmacies or supermarkets for wound sterilization and hair bleaching.
Vinoxide-HTC (a home-brew product containing a low level of peracetic acid ~0.15% and hydrogen peroxide ~2.3%). See this summary since it is not a commercial product.

Virkon-S (a commercial peroxide disinfectant with long life) made for the veterinary industry. Used for animal wound sterilization, and disinfecting anything from horse stalls through chicken coops to cage-bird aviaries.

Other sterilants are infrequently used in home plant tissue culture (if ever), but are used for commercial sterilization:

Peracetic acid CH3.COOOH (used in low concentrations for wastewater disinfecting, available at 35% as a commercial product). PAA (aka peroxyacetic acid) is a 0.15% component of Vinoxide-HTC (see summary sheet).
Ozone O3 (a very strong oxidant, but not available for home tissue culture)
Ultra-violet (UV) light (might be useful in home tissue culture, worth trying but protect eyes)
Chlorine dioxide ClO2 (not easily available for home tissue culture)

Most of these chemical agents act through a process of general oxidation. In other words, the action is almost non-specific to any organism, but is based on the agent attacking the cell wall through oxidation, leading to its rupture and the death of the cell through this cause and residual oxidation. Stronger oxidants release more energy per molecular interaction, and can therefore destroy stronger bonds. They often go together with shorter exposure times so as to not destroy wanted explant cells.